What Function Do Platelets Play in Inflammation and Bacterial and Viral Infections?

The article presents the function of platelets in inflammation as well as in bacterial and viral infections, which are the result of their reaction with the endovascular environment, including cells of damaged vascular endothelium and cells of the immune system. This role of platelets is conditioned by biologically active substances present in their granules and in their specific structures - EV (extracellular vesicles).

Possible therapeutic effects of Nigella sativa and its thymoquinone on COVID-19

CONTEXT

COVID-19 is a novel coronavirus that causes a severe infection in the respiratory system. Nigella sativa L. (Ranunculaceae) is an annual flowering plant used traditionally as a natural food supplement and multipurpose medicinal agent.

OBJECTIVE

The possible beneficial effects of N. sativa, and its constituent, thymoquinone (TQ) on COVID-19 were reviewed.

METHODS

The key words including, COVID-19, N. sativa, thymoquinone, antiviral effects, anti-inflammatory and immunomodulatory effects in different databases such as Web of Science (ISI), PubMed, Scopus, and Google Scholar were searched from 1990 up to February 2021.

RESULTS

The current literature review showed that N. sativa and TQ reduced the level of pro-inflammatory mediators including, IL-2, IL-4, IL-6, and IL-12, while enhancing IFN-γ. Nigella sativa and TQ increased the serum levels of IgG1 and IgG2a, and improved pulmonary function tests in restrictive respiratory disorders.

DISCUSSION AND CONCLUSIONS

These preliminary data of molecular docking, animal, and clinical studies propose N. sativa and TQ might have beneficial effects on the treatment or control of COVID-19 due to antiviral, anti-inflammatory and immunomodulatory properties as well as bronchodilatory effects. The efficacy of N. sativa and TQ on infected patients with COVID-19 in randomize clinical trials will be suggested.

l-Arginine and COVID-19: An Update

l-Arginine is involved in many different biological processes and recent reports indicate that it could also play a crucial role in the coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Herein, we present an updated systematic overview of the current evidence on the functional contribution of L-Arginine in COVID-19, describing its actions on endothelial cells and the immune system and discussing its potential as a therapeutic tool, emerged from recent clinical experimentations.

Interplay between SARS-CoV-2-derived miRNAs, immune system, vitamin D pathway and respiratory system

The new coronavirus pandemic started in China in 2019. The intensity of the disease can range from mild to severe, leading to death in many cases. Despite extensive research in this area, the exact molecular nature of virus is not fully recognized; however, according to pieces of evidence, one of the mechanisms of virus pathogenesis is through the function of viral miRNAs. So, we hypothesized that SARS-CoV-2 pathogenesis may be due to targeting important genes in the host with its miRNAs, which involved in the respiratory system, immune pathways and vitamin D pathways, thus possibly contributing to disease progression and virus survival. Potential miRNA precursors and mature miRNA were predicted and confirmed based on the virus genome. The next step was to predict and identify their target genes and perform functional enrichment analysis to recognize the biological processes connected with these genes in the three pathways mentioned above through several comprehensive databases. Finally, cis-acting regulatory elements in 5' regulatory regions were analysed, and the analysis of available RNAseq data determined the expression level of genes. We revealed that thirty-nine mature miRNAs could theoretically derive from the SARS-CoV-2 genome. Functional enrichment analysis elucidated three highlighted pathways involved in SARS-CoV-2 pathogenesis: vitamin D, immune system and respiratory system. Our finding highlighted genes' involvement in three crucial molecular pathways and may help develop new therapeutic targets related to SARS-CoV-2.

Nutraceuticals in Viral Infections: An Overview of the Immunomodulating Properties

Nutraceuticals, including vitamin D, vitamin A, zinc, lactoferrin, polyphenols coenzyme Q, magnesium, and selenium, are implicated in the modulation of the complex molecular pathways involved in the immune response against viral pathogens. A common element of the activity of nutraceuticals is their ability to enhance the innate immune response against pathogens by acting on the major cellular subsets and inducing the release of pro-inflammatory cytokines and antimicrobial peptides. In some cases, this action is accompanied by a direct antimicrobial effect, as evidenced in the specific case of lactoferrin. Furthermore, nutraceuticals act through complex molecular mechanisms to minimize the damage caused by the activation of the immune system against pathogens, reducing the oxidative damage, influencing the antigen presentation, enhancing the differentiation and proliferation of regulatory T cells, driving the differentiation of lymphocyte subsets, and modulating the production of pro-inflammatory cytokines. In this paper, we review the main molecular mechanisms responsible for the immunomodulatory function of nutraceuticals, focusing on the most relevant aspects for the prevention and treatment of viral infections.

Why COVID-19 is Less Severe in Pediatric Patients?

Editorial message 

Lessons learned: new insights on the role of cytokines in COVID-19

In the midst of resurging COVID-19 cases, the second NIH/FDA virtual COVID-19 and Cytokines symposium was held on 1 December 2020, focusing on longitudinal studies of COVID-19 immunity, including long-term consequences, potential associations with autoimmunity and the multisystem inflammatory syndrome in children (MIS-C).

Assessment of Studies Evaluating Spinal Manipulative Therapy and Infectious Disease and Immune System Outcomes: A Systematic Review

IMPORTANCE

Claims that spinal manipulative therapy (SMT) can improve immune function have increased substantially during the COVID-19 pandemic and may have contributed to the rapid spread of both accurate and inaccurate information (referred to as an infodemic by the World Health Organization).

OBJECTIVE

To identify, appraise, and synthesize the scientific literature on the efficacy and effectiveness of SMT in preventing the development of infectious disease or improving disease-specific outcomes in patients with infectious disease and to examine the association between SMT and selected immunological, endocrine, and other physiological biomarkers.

EVIDENCE REVIEW

A literature search of MEDLINE, the Cumulative Index to Nursing and Allied Health Literature, the Index to Chiropractic Literature, the Cochrane Central Register of Controlled Trials, and Embase was conducted from inception to April 15, 2020. Randomized clinical trials and cohort studies were included. Eligible studies were critically appraised, and evidence with high and acceptable quality was synthesized using the Synthesis Without Meta-Analysis guideline.

FINDINGS

A total of 2593 records were retrieved; after exclusions, 50 full-text articles were screened, and 16 articles reporting the findings of 13 studies comprising 795 participants were critically appraised. The literature search found no clinical studies that investigated the efficacy or effectiveness of SMT in preventing the development of infectious disease or improving disease-specific outcomes among patients with infectious disease. Eight articles reporting the results of 6 high- and acceptable-quality RCTs comprising 529 participants investigated the effect of SMT on biomarkers. Spinal manipulative therapy was not associated with changes in lymphocyte levels or physiological markers among patients with low back pain or participants who were asymptomatic compared with sham manipulation, a lecture series, and venipuncture control groups. Spinal manipulative therapy was associated with short-term changes in selected immunological biomarkers among asymptomatic participants compared with sham manipulation, a lecture series, and venipuncture control groups.

CONCLUSIONS AND RELEVANCE

In this systematic review of 13 studies, no clinical evidence was found to support or refute claims that SMT was efficacious or effective in changing immune system outcomes. Although there were limited preliminary data from basic scientific studies suggesting that SMT may be associated with short-term changes in immunological and endocrine biomarkers, the clinical relevance of these findings is unknown. Given the lack of evidence that SMT is associated with the prevention of infectious diseases or improvements in immune function, further studies should be completed before claims of efficacy or effectiveness are made.

Obesity, COVID-19 and innate immunometabolism

As COVID-19 continues to spread worldwide, severe disease and mortality have been observed in obese patients. We discuss how obesity and obesity-associated factors such as ‘meta-flammation’, dietary fat intake and paradoxical suppression of the innate immune response within the pulmonary compartment may be crucial determinants in the host response to a novel viral pathogen. Modulation of immune cell bioenergetics and metabolic potential plays a central role in the innate immune response to infection, and as we strive to combat this new global health threat, immunometabolism of the innate immune system warrants attention.

Susceptibility and Severity of Viral Infections in Obesity: Lessons from Influenza to COVID-19. Does Leptin Play a Role?

The recent pandemic Sars-CoV2 infection and studies on previous influenza epidemic have drawn attention to the association between the obesity and infectious diseases susceptibility and worse outcome. Metabolic complications, nutritional aspects, physical inactivity, and a chronic unbalance in the hormonal and adipocytokine microenvironment are major determinants in the severity of viral infections in obesity. By these pleiotropic mechanisms obesity impairs immune surveillance and the higher leptin concentrations produced by adipose tissue and that characterize obesity substantially contribute to such immune response dysregulation. Indeed, leptin not only controls energy balance and body weight, but also plays a regulatory role in the interplay between energy metabolism and immune system. Since leptin receptor is expressed throughout the immune system, leptin may exert effects on cells of both innate and adaptive immune system. Chronic inflammatory states due to metabolic (i.e., obesity) as well as infectious diseases increase leptin concentrations and consequently lead to leptin resistance further fueling inflammation. Multiple factors, including inflammation and ER stress, contribute to leptin resistance. Thus, if leptin is recognized as one of the adipokines responsible for the low grade inflammation found in obesity, on the other hand, impairments of leptin signaling due to leptin resistance appear to blunt the immunologic effects of leptin and possibly contribute to impaired vaccine-induced immune responses. However, many aspects concerning leptin interactions with inflammation and immune system as well as the therapeutical approaches to overcome leptin resistance and reduced vaccine effectiveness in obesity remain a challenge for future research.

In the Age of Viral Pandemic, Can Ingredients Inspired by Human Milk and Infant Nutrition Be Repurposed to Support the Immune System?

In 2020, with the advent of a pandemic touching all aspects of global life, there is a renewed interest in nutrition solutions to support the immune system. Infants are vulnerable to infection and breastfeeding has been demonstrated to provide protection. As such, human milk is a great model for sources of functional nutrition ingredients, which may play direct roles in protection against viral diseases. This review aims to summarize the literature around human milk (lactoferrin, milk fat globule membrane, osteopontin, glycerol monolaurate and human milk oligosaccharides) and infant nutrition (polyunsaturated fatty acids, probiotics and postbiotics) inspired ingredients for support against viral infections and the immune system more broadly. We believe that the application of these ingredients can span across all life stages and thus apply to both pediatric and adult nutrition. We highlight the opportunities for further research in this field to help provide tangible nutrition solutions to support one's immune system and fight against infections.

SARS-CoV-2-mediated immune system activation and potential application in immunotherapy

Although novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-mediated pulmonary inflammation has recently attracted great attention, its pathology and pathogenesis are not clear. Notably, due to both its high infective and pathogenicity, SARS-CoV-2 infection may cause a severe sometimes fatal respiratory disease. A specific vaccine, which relies on the analysis of SARS-CoV-2 structural protein-derived antigenic peptides, is indispensable for restraining the spread and reducing the mortality of SARS-CoV-2. SARS-CoV-2 infections activate cytototxic, myeloid-derived suppressor cells, dendritic cells, macrophages, as well as natural killer, B, helper T, and regulatory T cells, thus further stimulating innate and antigen-specific immune responses. Nevertheless, many immune effector cells cause hyperinflammation and pulmonary immunopathology by releasing proinflammatory cytokines and chemokines, including interferon (IFN)-α, IFN-β, IFN-γ, monocyte chemoattractant protein-1, macrophage inflammatory protein (MIP)-1A, MIP1B, interleukin (IL)-1, IL-2, IL-4, IL-6, IL-7, IL-8, IL-9, IL-12, IL-17, and IL-18, platelet-derived growth factor, fibroblast growth factor, tumor necrosis factor-α, and induced protein 10. Interestingly, related products derived from SARS-CoV-2 are likely to trigger immune evasion. Therefore, investigating SARS-CoV-2-specific vaccines, blocking immunopathology, and prohibiting immune evasion are urgently required for treating SARS-CoV-2 infection. In this review, we emphatically illuminated the development of a SARS-CoV-2-specific vaccine based on the analysis of epitopes, also expounding the molecular mechanisms of SARS-CoV-2-mediated cytokine release syndrome. Furthermore, we comprehensively discussed SARS-CoV-2-associated immune evasion and lung immunopathology. Lastly, potential therapeutic strategies against SARS-CoV-2 were explored.

Changes in physiology and immune system during pregnancy and coronavirus infection: A review

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the 3rd epidemic coronavirus after severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV). Since December 2019, the outbreak of the Coronavirus Disease 2019 (COVID-19) caused by SARS-CoV-2 has aroused great attention around the world. Pregnant women and their fetuses have been concerned as a high-risk population. We explained why pregnant women are susceptible to coronavirus in terms of their adaptive changes in physiology and immune system during pregnancy, and described the associations between maternal clinical symptoms, perinatal outcomes and coronavirus infections.

COVID-19: Is there a role for immunonutrition in obese patient?

On December 12, 2019 a new coronavirus (SARS-CoV-2) emerged in Wuhan, China, triggering a pandemic of severe acute respiratory syndrome in humans (COVID-19). Today, the scientific community is investing all the resources available to find any therapy and prevention strategies to defeat COVID-19. In this context, immunonutrition can play a pivotal role in improving immune responses against viral infections. Immunonutrition has been based on the concept that malnutrition impairs immune function. Therefore, immunonutrition involves feeding enriched with various pharmaconutrients (Omega 3 Fatty Acids, Vitamin C, Arginine, Glutamine, Selenium, Zinc, Vitamin, E and Vitamin D) to modulate inflammatory responses, acquired immune response and to improve patient outcomes. In literature, significant evidences indicate that obesity, a malnutrition state, negatively impacts on immune system functionality and on host defense, impairing protection from infections. Immunonutrients can promote patient recovery by inhibiting inflammatory responses and regulating immune function. Immune system dysfunction is considered to increase the risk of viral infections, such as SARS-CoV-2, and was observed in different pathological situations. Obese patients develop severe COVID-19 sequelae, due to the high concentrations of TNF-α, MCP-1 and IL-6 produced in the meantime by visceral and subcutaneous adipose tissue and by innate immunity. Moreover, leptin, released by adipose tissue, helps to increase inflammatory milieu with a dysregulation of the immune response. Additionally, gut microbiota plays a crucial role in the maturation, development and functions of both innate and adaptive immune system, as well as contributing to develop obese phenotype. The gut microbiota has been shown to affect lung health through a vital crosstalk between gut microbiota and lungs, called the "gut-lung axis". This axis communicates through a bi-directional pathway in which endotoxins, or microbial metabolites, may affect the lung through the blood and when inflammation occurs in the lung, this in turn can affect the gut microbiota. Therefore, the modulation of gut microbiota in obese COVID-19 patients can play a key role in immunonutrition therapeutic strategy. This umbrella review seeks to answer the question of whether a nutritional approach can be used to enhance the immune system's response to obesity in obese patients affected by COVID-19.

Extrapulmonary Clinical Manifestations in COVID-19 Patients

COVID-19 manifestations in symptomatic patients can be in the form of pneumonia, acute respiratory syndrome, and multiple organ dysfunction as well. Renal complications, gastrointestinal dysfunctions, endocrine system disorders, myocardial dysfunction and arrhythmia, neurological dysfunctions, dermatological symptoms, hematological manifestations, and thromboinflammation are among the reported extrapulmonary complications. Moreover, the presence of coagulopathy, excessive and dysregulated immune responses, and autoimmunity by COVID-19 patients is considerable. The pathogenesis of infection entails the entry of the virus via receptors on cells, principally angiotensin-converting enzyme 2 receptors. Direct virus damage coupled with indirect effects of viral infection including thromboinflammation, dysfunction of the immune system, and dysregulation of the renin-angiotensin system leads to multiple organ failure. This review outlines the extrapulmonary organ-specific complications and their pathophysiology and epidemiology.

Towards a pharmacochemical hypothesis of the prophylaxis of SARS-CoV-2 by psychoactive substances

An increasing body of evidence suggests a protective effect of some psychoactive substances against SARS-CoV-2 (Severe Acute Respiratory Syndrome coronavirus type 2). Recent findings suggest that patients with psychiatric disorders are less affected by SARS-CoV-2 than their caregivers, which may seem surprising given some of the frequent risk factors for an unfavorable course of the disease (e.g., obesity, diabetes, cardiovascular and pulmonary diseases). We propose here a mixed pharmacoepidemiological and pharmacochemical hypothesis to explain these findings. A number of psychotropic drugs exhibit activities against coronaviruses (Middle East Respiratory Syndrome coronavirus (MERS-CoV), the Severe Acute Respiratory Syndrome coronavirus (SARS-CoV-1) and the Infectious Bronchitis Virus (IBV)) and have been put forward as potentially anti-SARS-CoV-2. These treatments include numerous mee-too drugs (chemically and pharmacologically linked to those which have demonstrated anti-SARS-CoV-2 efficacy) which are frequently prescribed in psychiatric settings. Taken alone or in polypharmacy, these drugs could have a prophylactic anti-SARS-CoV-2 effect, explaining the unexpectedly low proportion of patients with psychiatric disorders and COVID-19. Associated factors such as nicotine can also be considered in the context of a broad chemoprophylactic hypothesis in patients with psychiatric disorders taking different psychoactive substances.

[Measles vaccination: why and how?]

The measles virus is highly contagious and may hit non-immune populations very hard, as observed on remote islands. The first live-attenuated measles virus vaccine was registered in the United States in 1963, and was imported to the Netherlands from 1968 onwards. Production was taken over by the National Institute for Public Health (RIV). Because the burden of disease was still high, measles vaccination was introduced into the Dutch National Immunisation Programme in 1976; since 1987 this has been in the form of the combined measles, mumps and rubella (MMR) vaccination. The MMR vaccine was also initially imported and later manufactured by the National Institute for Public Health and the Environment (RIVM). Since then, measles epidemics have almost exclusively affected unvaccinated populations. Vaccinated individuals are thus well-protected, as are unvaccinated individuals as long as the rate of vaccination in the surrounding population is sufficiently high. Unvaccinated individuals who travel to countries where measles is endemic are still at a higher risk. Recent studies show that measles not only has the classical symptoms, but also damages the immune system.

[The measles paradox explained: how measles virus both suppresses and activates the immune system]

Measles virus infection causes immune suppression, resulting in increased susceptibility to opportunistic infectious diseases. At the same time, the infection induces a strong virus-specific immune response, resulting in lifelong protection against measles. Based on studies in tissue cultures, laboratory animals and patients, we have unravelled the mechanism by which measles affects the immune system, thereby explaining the 'measles paradox'. Recent studies based on blood samples of unvaccinated children in the Orthodox Protestant community collected before, during and after measles have provided further evidence of this mechanism. Results show that measles causes 'immune amnesia'. This article summarizes the results of these studies from a clinical perspective.

How the COVID-19 Overcomes the Battle? An Approach to Virus Structure

Coronaviruses primarily cause zoonotic infections, however in the past few decades several interspecies transmissions have occurred, the last one by SARS-CoV-2, causing COVID-19 pandemic, posing serious threat to global health. The SARS-CoV-2 spike (S) protein plays an important role in viral attachment, fusion and entry. However, other structural and non-structural SARS-CoV-2 proteins are potential influencers in virus pathogenicity. Among these proteins; Orf3, Orf8, and Orf10 show the least homology to SARSCoV proteins and therefore should be further studied for their abilities to modulate antiviral and inflammatory responses. Here, we discuss how SARS-COV-2 interacts with our immune system.

Impact of SARS-CoV-2 infection on neurodegenerative and neuropsychiatric diseases: a delayed pandemic?

INTRODUCTION

SARS-CoV-2 was first detected in December 2019 in the Chinese city of Wuhan and has since spread across the world. At present, the virus has infected over 1.7 million people and caused over 100 000 deaths worldwide. Research is currently focused on understanding the acute infection and developing effective treatment strategies. In view of the magnitude of the epidemic, we conducted a speculative review of possible medium- and long-term neurological consequences of SARS-CoV-2 infection, with particular emphasis on neurodegenerative and neuropsychiatric diseases of neuroinflammatory origin, based on the available evidence on neurological symptoms of acute SARS-CoV-2 infection.

DEVELOPMENT

We systematically reviewed the available evidence about the pathogenic mechanisms of SARS-CoV-2 infection, the immediate and lasting effects of the cytokine storm on the central nervous system, and the consequences of neuroinflammation for the central nervous system.

CONCLUSIONS

SARS-CoV-2 is a neuroinvasive virus capable of triggering a cytokine storm, with persistent effects in specific populations. Although our hypothesis is highly speculative, the impact of SARS-CoV-2 infection on the onset and progression of neurodegenerative and neuropsychiatric diseases of neuroinflammatory origin should be regarded as the potential cause of a delayed pandemic that may have a major public health impact in the medium to long term. Cognitive and neuropsychological function should be closely monitored in COVID-19 survivors.

New insights into intestinal phages

The intestinal microbiota plays important roles in human health. This last decade, the viral fraction of the intestinal microbiota, composed essentially of phages that infect bacteria, received increasing attention. Numerous novel phage families have been discovered in parallel with the development of viral metagenomics. However, since the discovery of intestinal phages by d'Hérelle in 1917, our understanding of the impact of phages on gut microbiota structure remains scarce. Changes in viral community composition have been observed in several diseases. However, whether these changes reflect a direct involvement of phages in diseases etiology or simply result from modifications in bacterial composition is currently unknown. Here we present an overview of the current knowledge in intestinal phages, their identity, lifestyles, and their possible effects on the gut microbiota. We also gather the main data on phage interactions with the immune system, with a particular emphasis on recent findings.

Targeting the gut-lung microbiota axis by means of a high-fibre diet and probiotics may have anti-inflammatory effects in COVID-19 infection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) 1 is a 2019 novel coronavirus, which only in the European area has led to more than 300,000 cases with at least 21,000 deaths. This manuscript aims to speculate that the manipulation of the microbial patterns through the use of probiotics and dietary fibers consumption may contribute to reduce inflammation and strengthen the immune system response in COVID-19 infection. The reviews of this paper are available via the supplemental material section.

ADAR1 function affects HPV replication and is associated to recurrent human papillomavirus-induced dysplasia in HIV coinfected individuals

Infection by human papillomavirus (HPV) alters the microenvironment of keratinocytes as a mechanism to evade the immune system. A-to-I editing by ADAR1 has been reported to regulate innate immunity in response to viral infections. Here, we evaluated the role of ADAR1 in HPV infection in vitro and in vivo. Innate immune activation was characterized in human keratinocyte cell lines constitutively infected or not with HPV. ADAR1 knockdown induced an innate immune response through enhanced expression of RIG-I-like receptors (RLR) signaling cascade, over-production of type-I IFNs and pro-inflammatory cytokines. ADAR1 knockdown enhanced expression of HPV proteins, a process dependent on innate immune function as no A-to-I editing could be identified in HPV transcripts. A genetic association study was performed in a cohort of HPV/HIV infected individuals followed for a median of 6 years (range 0.1-24). We identified the low frequency haplotype AACCAT significantly associated with recurrent HPV dysplasia, suggesting a role of ADAR1 in the outcome of HPV infection in HIV+ individuals. In summary, our results suggest that ADAR1-mediated innate immune activation may influence HPV disease outcome, therefore indicating that modification of innate immune effectors regulated by ADAR1 could be a therapeutic strategy against HPV infection.

Viral dynamics of an HIV stochastic model with cell-to-cell infection, CTL immune response and distributed delays

Recent studies have demonstrated that both virus-to-cell infection and cell-to-cell transmission play an important role in the process of HIV infection. In this paper, stochastic perturbation is introduced into HIV model with virus-to-cell infection, cell-to-cell transmission, CTL immune response and three distributed delays. The stochastic integro-delay differential equations is transformed into a degenerate stochastic differential equations. Through rigorous analysis of the model, we obtain the solution is unique, positive and global. By constructing appropriate Lyapunov functions, the existence of the stationary Markov process is derived when the critical condition is bigger than one. Furthermore, the extinction of the virus for sufficiently big noise intensity is established. Numerically, we investigate that the small noise intensity of fluctuations could help to sustain the number of virions and CTL immune response within a certain range, while the big noise intensity may be beneficial to the extinction of the virus. We also examine that the influence of random fluctuations on model dynamics may be more significant than that of the delay.

How the gut microbiome regulates host immune responses to viral vaccines

The co-evolution of the microbiota and immune system has forged a mutually beneficial relationship. This relationship allows the host to maintain the balance between active immunity to pathogens and vaccines and tolerance to self-antigens and food antigens. In children living in low-income and middle-income countries, undernourishment and repetitive gastrointestinal infections are associated with the failure of oral vaccines. Intestinal dysbiosis associated with these environmental influences, as well as some host-related factors, compromises immune responses and negatively impacts vaccine efficacy. To understand how immune responses to viral vaccines can be optimally modulated, mechanistic studies of the relationship between the microbiome, host genetics, viral infections and the development and function of the immune system are needed. We discuss the potential role of the microbiome in modulating vaccine responses in the context of a growing understanding of the relationship between the gastrointestinal microbiota, host related factors (including histo-blood group antigens) and resident immune cell populations.

Cross-talk of cutaneous beta human papillomaviruses and the immune system: determinants of disease penetrance

Human papillomaviruses (HPVs) infect the epithelia of skin or mucosa, where they can induce hyperproliferative lesions. More than 220 different HPV types have been characterized and classified into five different genera. Mucosal high-risk HPVs are causative for cancers of the anogenital region and oropharynx. Clinical data from patients with the rare genetic disorder epidermodysplasia verruciformis (EV) indicate that genus beta-HPVs cooperate with ultraviolet (UV) radiation in the development of cutaneous squamous cell carcinoma. In addition, epidemiological and biological findings indicate that beta-HPV types play a role in UV-mediated skin carcinogenesis also in non-EV individuals. However, the mechanisms used by these cutaneous viruses to promote epithelial carcinogenesis differ significantly from those of mucosal HPVs. Recent studies point to a delicate cross-talk of beta-HPVs with the cell-autonomous immunity of the host keratinocytes and the local immune microenvironment that eventually determines the fate of cutaneous HPV infection and the penetrance of disease. This review gives an overview of the critical interactions of genus beta-HPVs with the local immune system that allow the virus to complete its life cycle, to escape from extrinsic immunity, and eventually to cause chronic inflammation contributing to skin carcinogenesis. This article is part of the theme issue 'Silent cancer agents: multi-disciplinary modelling of human DNA oncoviruses'.

Dynamics of the tumor-immune-virus interactions: Convergence conditions to tumor-only or tumor-free equilibrium points

In the present paper convergence dynamics of one tumor-immune-virus model is examined with help of the localization method of compact invariant sets and the LaSalle theorem. This model was elaborated by Eftimie et al. in 2016. It is shown that this model possesses the Lagrange stability property of positive half-trajectories and ultimate upper bounds for compact invariant sets are obtained. Conditions of convergence dynamics are found. It is explored the case when any trajectory is attracted to one of tumor-only equilibrium points or tumor-free equilibrium points. Further, it is studied ultimate dynamics of one modification of Eftimie et al. model in which the immune cells injection is included. This modified system possesses the global tumor cells eradication property if the influx rate of immune cells exceeds some value which is estimated. Main results are expressed in terms simple algebraic inequalities imposed on model and treatment parameters.

Destabilized adaptive influenza variants critical for innate immune system escape are potentiated by host chaperones

The threat of viral pandemics demands a comprehensive understanding of evolution at the host-pathogen interface. Here, we show that the accessibility of adaptive mutations in influenza nucleoprotein at fever-like temperatures is mediated by host chaperones. Particularly noteworthy, we observe that the Pro283 nucleoprotein variant, which (1) is conserved across human influenza strains, (2) confers resistance to the Myxovirus resistance protein A (MxA) restriction factor, and (3) critically contributed to adaptation to humans in the 1918 pandemic influenza strain, is rendered unfit by heat shock factor 1 inhibition-mediated host chaperone depletion at febrile temperatures. This fitness loss is due to biophysical defects that chaperones are unavailable to address when heat shock factor 1 is inhibited. Thus, influenza subverts host chaperones to uncouple the biophysically deleterious consequences of viral protein variants from the benefits of immune escape. In summary, host proteostasis plays a central role in shaping influenza adaptation, with implications for the evolution of other viruses, for viral host switching, and for antiviral drug development.

In silico and ex vivo approaches indicate immune pressure on capsid and non-capsid regions of coxsackie B viruses in the human system

Coxsackie B Virus (CBV) infection has been linked to the aetiology of type 1 diabetes (T1D) and vaccination has been proposed as prophylaxis for disease prevention. Serum neutralising antibodies and the presence of viral protein and RNA in tissues have been common tools to examine this potential disease relationship, whilst the role of anti-CBV cytotoxic T cell responses and their targets have not been studied. To address this knowledge gap, we augmented conventional HLA-binding predictive algorithm-based epitope discovery by cross-referencing epitopes with sites of positive natural selection within the CBV3 viral genome, identified using mixed effects models of evolution. Eight epitopes for the common MHC class I allele HLA-A*0201 occur at sites that appear to be positively selected. Furthermore, such epitopes span the viral genome, indicating that effective anti-viral responses may not be restricted to the capsid region. To assess the spectrum of IFNy responses in non-diabetic subjects and recently diagnosed type 1 diabetes (T1D) patients, we stimulated PBMC ex vivo with pools of synthetic peptides based on component-restricted sequences identified in silico. We found responders were more likely to recognize multiple rather than a single CBV peptide pool, indicating that the natural course of infection results in multiple targets for effector memory responses, rather than immunodominant epitopes or viral components. The finding that anti-CBV CD8 T cell immunity is broadly targeted has implications for vaccination strategies and studies on the pathogenesis of CBV-linked diseases.

Up in Arms: Immune and Nervous System Response to Sea Star Wasting Disease

Echinoderms, positioned taxonomically at the base of deuterostomes, provide an important system for the study of the evolution of the immune system. However, there is little known about the cellular components and genes associated with echinoderm immunity. The 2013-2014 sea star wasting disease outbreak is an emergent, rapidly spreading disease, which has led to large population declines of asteroids in the North American Pacific. While evidence suggests that the signs of this disease, twisting arms and lesions, may be attributed to a viral infection, the host response to infection is still poorly understood. In order to examine transcriptional responses of the sea star Pycnopodia helianthoides to sea star wasting disease, we injected a viral sized fraction (0.2 μm) homogenate prepared from symptomatic P. helianthoides into apparently healthy stars. Nine days following injection, when all stars were displaying signs of the disease, specimens were sacrificed and coelomocytes were extracted for RNA-seq analyses. A number of immune genes, including those involved in Toll signaling pathways, complement cascade, melanization response, and arachidonic acid metabolism, were differentially expressed. Furthermore, genes involved in nervous system processes and tissue remodeling were also differentially expressed, pointing to transcriptional changes underlying the signs of sea star wasting disease. The genomic resources presented here not only increase understanding of host response to sea star wasting disease, but also provide greater insight into the mechanisms underlying immune function in echinoderms.

Enterovirus71 (EV71) utilise host microRNAs to mediate host immune system enhancing survival during infection

Hand, Foot and Mouth Disease (HFMD) is a self-limiting viral disease that mainly affects infants and children. In contrast with other HFMD causing enteroviruses, Enterovirus71 (EV71) has commonly been associated with severe clinical manifestation leading to death. Currently, due to a lack in understanding of EV71 pathogenesis, there is no antiviral therapeutics for the treatment of HFMD patients. Therefore the need to better understand the mechanism of EV71 pathogenesis is warranted. We have previously reported a human colorectal adenocarcinoma cell line (HT29) based model to study the pathogenesis of EV71. Using this system, we showed that knockdown of DGCR8, an essential cofactor for microRNAs biogenesis resulted in a reduction of EV71 replication. We also demonstrated that there are miRNAs changes during EV71 pathogenesis and EV71 utilise host miRNAs to attenuate antiviral pathways during infection. Together, data from this study provide critical information on the role of miRNAs during EV71 infection.

Immunologic strategies for HIV-1 remission and eradication

Antiretroviral therapy (ART) is able to suppress HIV-1 replication indefinitely in individuals who have access to these medications, are able to tolerate these drugs, and are motivated to take them daily for life. However, ART is not curative. HIV-1 persists indefinitely during ART as quiescent integrated DNA within memory CD4(+) T cells and perhaps other long-lived cellular reservoirs. In this Review, we discuss the role of the immune system in the establishment and maintenance of the latent HIV-1 reservoir. A detailed understanding of how the host immune system shapes the size and distribution of the viral reservoir should lead to the development of a new generation of immune-based therapeutics, which may eventually contribute to a curative intervention.

Influenza, immune system, and pregnancy

Influenza is a major health problem worldwide. Both seasonal influenza and pandemics take a major toll on the health and economy of our country. The present review focuses on the virology and complex immunology of this RNA virus in general and in relation to pregnancy. The goal is to attempt to explain the increased morbidity and mortality seen in infection during pregnancy. We discuss elements of innate and adaptive immunity as well as placental cellular responses to infection. In addition, we delineate findings in animal models as well as human disease. Increased knowledge of maternal and fetal immunologic responses to influenza is needed. However, enhanced understanding of nonimmune, pregnancy-specific factors influencing direct interaction of the virus with host cells is also important for the development of more effective prevention and treatment options in the future.

Flavivirus NS1 structures reveal surfaces for associations with membranes and the immune system

Flaviviruses, the human pathogens responsible for dengue fever, West Nile fever, tick-borne encephalitis, and yellow fever, are endemic in tropical and temperate parts of the world. The flavivirus nonstructural protein 1 (NS1) functions in genome replication as an intracellular dimer and in immune system evasion as a secreted hexamer. We report crystal structures for full-length, glycosylated NS1 from West Nile and dengue viruses. The NS1 hexamer in crystal structures is similar to a solution hexamer visualized by single-particle electron microscopy. Recombinant NS1 binds to lipid bilayers and remodels large liposomes into lipoprotein nanoparticles. The NS1 structures reveal distinct domains for membrane association of the dimer and interactions with the immune system and are a basis for elucidating the molecular mechanism of NS1 function.

Host immune status and response to hepatitis E virus infection

Hepatitis E virus (HEV), identified over 30 years ago, remains a serious threat to life, health, and productivity in developing countries where access to clean water is limited. Recognition that HEV also circulates as a zoonotic and food-borne pathogen in developed countries is more recent. Even without treatment, most cases of HEV-related acute viral hepatitis (with or without jaundice) resolve within 1 to 2 months. However, HEV sometimes leads to acute liver failure, chronic infection, or extrahepatic symptoms. The mechanisms of pathogenesis appear to be substantially immune mediated. This review covers the epidemiology of HEV infection worldwide, the humoral and cellular immune responses to HEV, and the persistence and protection of antibodies produced in response to both natural infection and vaccines. We focus on the contributions of altered immune states (associated with pregnancy, human immunodeficiency virus [HIV], and immunosuppressive agents used in cancer and transplant medicine) to the elevated risks of chronic infection (in immunosuppressed/immunocompromised patients) and acute liver failure and mortality (among pregnant women). We conclude by discussing outstanding questions about the immune response to HEV and interactions with hormones and comorbid conditions. These questions take on heightened importance now that a vaccine is available.

Potential role of HPA axis and sympathetic nervous responses in depletion of B cells induced by H9N2 avian influenza virus infection

Except severe pulmonary disease caused by influenza virus infection, an impaired immune system is also a clinic characteristic. However, the mechanism(s) of influenza virus infection-induced depletion of B cells was unknown. Here, we compared the effect of two variant virulence H9N2 virus infections on mouse B cells. Our study found that the infection with highly pathogenic virus (V) of led to depletion of spleen B cells and bone marrow (BM) early B cells, compared to lowly pathogenic virus (Ts). Moreover, high apoptosis and cell cycle arrest in spleen and BM were detected, suggesting important factors for the reduction of B cells in both organs. Further, this effect was not caused by virus replication in spleen and BM. Compared to Ts virus infection, V virus resulted in higher glucocorticoids (GCs) and lower leptin level in plasma. Intraperitoneal GCs receptor antagonist RU486 injection was sufficient to prevent the loss of spleen B cell and BM pro- and immature B cells, but similar result was not observed in leptin-treated mice. Depletion of spleen B cells and BM pro-B cells was also reversed by chemical sympathectomy mediated by the norepinephrine (NE) analog 6-hydroxydopamine (6-OHDA), but the treatment didn't affect the GCs level. This study demonstrated that depletion of B cells induced by H9N2 AIV was dependent on HPA axis and sympathetic response.

Immunology of chronic BVDV infections

Bovine viral diarrhea virus can maintain prolonged infections within immunoprivileged sites after an otherwise transient infection of a cow, calf, or bull. Various sites provide unique niches for viral replication which are not susceptible to the complete surveillance commonly provided by the bovine immune system. Evidence indicates that pestiviral infections may be significantly prolonged within ovarian tissue, testicular tissue, central nervous system tissue, and circulating white blood cells. Within avascular portions of the ovarian follicle, granulosa cells and oocytes may maintain BVDV infections which cannot be attacked by cell-mediated immunity. When infections occur within seminiferous tubules in testicular tissue, similar protection from the immune system is provided for BVDV by the blood-testes barrier. Likewise, the blood-brain barrier has been hypothesized to provide protection for BVDV in a case involving neuropathology associated with immunohistochemical detection of BVDV. Furthermore, infections of circulating white blood cells may perturb their stimulation of an adaptive immune response and facilitate chronic infection of these cells. Thus, BVDV has demonstrated an ability to maintain prolonged viral infections in immunoprivileged sites within its natural host. The role of chronic infections in maintaining and disseminating BVDV within the cattle population and heterologous host species remains to be fully understood.

Chronic fatigue syndrome, the immune system and viral infection

The chronic fatigue syndrome (CFS), as defined by recent criteria, is a heterogeneous disorder with a common set of symptoms that often either follows a viral infection or a period of stress. Despite many years of intense investigation there is little consensus on the presence, nature and degree of immune dysfunction in this condition. However, slightly increased parameters of inflammation and pro-inflammatory cytokines such as interleukin (IL) 1, IL6 and tumour necrosis factor (TNF) α are likely present. Additionally, impaired natural killer cell function appears evident. Alterations in T cell numbers have been described by some and not others. While the prevalence of positive serology for the common herpes viruses appears no different from healthy controls, there is some evidence of viral persistence and inadequate containment of viral replication. The ability of certain herpes viruses to impair the development of T cell memory may explain this viral persistence and the continuation of symptoms. New therapies based on this understanding are more likely to produce benefit than current methods.

Virology. An exit strategy for measles virus

A receptor for measles virus on epithelial cells reveals how the virus accesses the respiratory tract.

[Two different receptors for wild type measles virus]

Measles is a highly contagious acute viral disease characterized by a maculopapular rash. It causes severe and temporary immune suppression and is often accompanied by secondary bacterial infections. In 2000, signaling lymphocyte activation molecule (SLAM) was identified as a receptor for measles virus (MV). Observations that SLAM is expressed on cells of the immune system provided a good explanation for the lymphotropic and immunosuppressive nature of MV. However, molecular mechanisms of highly contagious nature of MV have remained unclear. Previously we have demonstrated that MV has an intrinsic ability to infect polarized epithelial cells by using a receptor other than SLAM. Recently, nectin4, a cellular adhesion junction molecule, was identified as the epithelial cell receptor for MV. Understanding the molecular mechanisms of MV to infect both epithelial and immune cells provides a deep insight into measles pathogenesis.

[Immunosuppression in dogs and pigs infected with canine distemper virus]

Immunosuppression manifesting itself as leukopenia and a considerably lower lymphocyte proliferative response to T- and B-cell mitogens develops in pigs and dogs within 2-3 weeks after intramuscular or oral infection with canine distemper virus (CDV). CDV antigens are detectable in the oral secretions of the animals within 2-2.5 week after infection.

Alcohol and hepatitis C virus--interactions in immune dysfunctions and liver damage

Hepatitis C virus infection affects 170 million people worldwide, and the majority of individuals exposed to HCV develop chronic hepatitis leading to progressive liver damage, cirrhosis, and hepatocellular cancer. The natural history of HCV infection is influenced by genetic and environmental factors of which chronic alcohol use is an independent risk factor for cirrhosis in HCV-infected individuals. Both the hepatitis C virus and alcohol damage the liver and result in immune alterations contributing to both decreased viral clearance and liver injury. This review will capture the major components of the interactions between alcohol and HCV infection to provide better understanding for the molecular basis of the dangerous combination of alcohol use and HCV infection. Common targets of HCV and alcohol involve innate immune recognition and dendritic cells, the critical cell type in antigen presentation and antiviral immunity. In addition, both alcohol and HCV affect intracellular processes critical for hepatocyte and immune cell functions including mitochondrial and proteasomal activation. Finally, both chronic alcohol use and hepatitis C virus infection increase the risk of hepatocellular cancer. The common molecular mechanisms underlying the pathological interactions between alcohol and HCV include the modulation of cytokine production, lipopolysaccharide (LPS)-TLR4 signaling, and reactive oxygen species (ROS) production. LPS-induced chronic inflammation is not only a major cause of progressive liver injury and fibrosis, but it can also contribute to modification of the tissue environment and stem cells to promote hepatocellular cancer development. Alteration of these processes by alcohol and HCV produces an environment of impaired antiviral immune response, greater hepatocellular injury, and activation of cell proliferation and dedifferentiation.

Identification of target cells for Goose parvovirus infection in the immune system organs

Target cells for Goose parvovirus (GPV) in natural infection are still unknown. In this study, immune system organs namely the spleen, bone marrow, thymus, bursa of Fabricius, and blood of experimentally GPV-infected goslings were examined by an immunoassay and flow cytometry for the presence of viral antigen and by a PCR for viral genome. The results indicated that the virus replicated in some cells of the spleen and bone marrow, but not in peripheral blood lymphocytes (PBLs). These data suggested that some cell populations in the spleen and bone marrow were targets for GPV infection. In addition, the immunoassay used for the detection of GPV was found comparable with a PCR in reliability and sensitivity.

PB1-F2 proteins from H5N1 and 20 century pandemic influenza viruses cause immunopathology

With the recent emergence of a novel pandemic strain, there is presently intense interest in understanding the molecular signatures of virulence of influenza viruses. PB1-F2 proteins from epidemiologically important influenza A virus strains were studied to determine their function and contribution to virulence. Using 27-mer peptides derived from the C-terminal sequence of PB1-F2 and chimeric viruses engineered on a common background, we demonstrated that induction of cell death through PB1-F2 is dependent upon BAK/BAX mediated cytochrome c release from mitochondria. This function was specific for the PB1-F2 protein of A/Puerto Rico/8/34 and was not seen using PB1-F2 peptides derived from past pandemic strains. However, PB1-F2 proteins from the three pandemic strains of the 20^th century and a highly pathogenic strain of the H5N1 subtype were shown to enhance the lung inflammatory response resulting in increased pathology. Recently circulating seasonal influenza A strains were not capable of this pro-inflammatory function, having lost the PB1-F2 protein's immunostimulatory activity through truncation or mutation during adaptation in humans. These data suggest that the PB1-F2 protein contributes to the virulence of pandemic strains when the PB1 gene segment is recently derived from the avian reservoir.

There is presently great interest in understanding how influenza viruses cause disease. In this paper, we explore the role of the influenza virus PB1-F2 protein in disease. We show that the ability of the protein to cause cell death is mediated through a mitochondrial death pathway controlled by proteins called BAX or BAK. However, this function of the protein only seems to be relevant to a restricted set of viruses and not past pandemic strains. Instead, the ability to generate inflammation in the lung proves to be a common trait of all past pandemic strains as well as the H5N1 highly pathogenic avian influenza strains which remain a significant pandemic threat. It appears likely that this pro-inflammatory phenotype is a characteristic of viruses emerging from the avian reservoir and is therefore important for new strains that cross the species barrier and establish themselves in humans. During circulation and adaptation in the mammalian lung, this function is typically lost. Of note, the novel 2009 H1N1 pandemic strain does not express a full-length PB1-F2. Were it to acquire a fully functional, inflammatory PB1-F2 through reassortment, this could herald greatly enhanced disease potential.

Effect of the novel influenza A (H1N1) virus in the human immune system

Background

The pandemic by the novel H1N1 virus has created the need to study any probable effects of that infection in the immune system of the host.

Methodology/Principal Findings

Blood was sampled within the first two days of the presentation of signs of infection from 10 healthy volunteers; from 18 cases of flu-like syndrome; and from 31 cases of infection by H1N1 confirmed by reverse RT-PCR. Absolute counts of subtypes of monocytes and of lymphocytes were determined after staining with monoclonal antibodies and analysis by flow cytometry. Peripheral blood mononuclear cells (PBMCs) were isolated from patients and stimulated with various bacterial stimuli. Concentrations of tumour necrosis factor-alpha, interleukin (IL)-1beta, IL-6, IL-18, interferon (FN)-alpha and of IFN-gamma were estimated in supernatants by an enzyme immunoassay. Infection by H1N1 was accompanied by an increase of monocytes. PBMCs of patients evoked strong cytokine production after stimulation with most of bacterial stimuli. Defective cytokine responses were shown in response to stimulation with phytohemagglutin and with heat-killed Streptococcus pneumoniae. Adaptive immune responses of H1N1-infected patients were characterized by decreases of CD4-lymphocytes and of B-lymphocytes and by increase of T-regulatory lymphocytes (Tregs).

Conclusions/Significance

Infection by the H1N1 virus is accompanied by a characteristic impairment of the innate immune responses characterized by defective cytokine responses to S.pneumoniae. Alterations of the adaptive immune responses are predominated by increase of Tregs. These findings signify a predisposition for pneumococcal infections after infection by H1N1 influenza.

An uncommon presentation of the co-existence of morphea and vitiligo in a patient with chronic hepatitis B virus infection: is there a possible association with autoimmunity?

A 30-year-old man presented with indurated violaceous plaques all over his body that had been present for 7 months. The patient had also had vitiligo for 3.5 years, and hepatitis B virus (HBV) infection and cirrhosis for a 2-year period. Histopathologic examination of the indurated plaques confirmed the diagnosis of morphea. Localized scleroderma and vitiligo have only rarely been reported to occur simultaneously. Although the etiologies of vitiligo and morphea are both uncertain, their association with autoimmune diseases favors an autoimmune hypothesis. Both vitiligo and morphea might have appeared coincidentally. However, this association could be significant because it may be related to the presence of HBV and alterations in the immune system that are caused by this virus. Therefore, this rare combination of vitiligo and morphea in a patient with chronic HBV infection warrants attention because it suggests a possible immunologic association, which may merit future study.

Nora virus persistent infections are not affected by the RNAi machinery

Drosophila melanogaster is widely used to decipher the innate immune system in response to various pathogens. The innate immune response towards persistent virus infections is among the least studied in this model system. We recently discovered a picorna-like virus, the Nora virus which gives rise to persistent and essentially symptom-free infections in Drosophila melanogaster. Here, we have used this virus to study the interaction with its host and with some of the known Drosophila antiviral immune pathways. First, we find a striking variability in the course of the infection, even between flies of the same inbred stock. Some flies are able to clear the Nora virus but not others. This phenomenon seems to be threshold-dependent; flies with a high-titer infection establish stable persistent infections, whereas flies with a lower level of infection are able to clear the virus. Surprisingly, we find that both the clearance of low-level Nora virus infections and the stability of persistent infections are unaffected by mutations in the RNAi pathways. Nora virus infections are also unaffected by mutations in the Toll and Jak-Stat pathways. In these respects, the Nora virus differs from other studied Drosophila RNA viruses.

Effects of immune system diversity and physical variation of immunotypic mixing on the dynamics of rabies in bats

The ecology and life history of rabies viruses in bats suggest a need for an integrated modelling treatment that extends beyond traditional epidemiological approaches. We modify our adaptive modelling approach to investigate the effects of immune system structure and immunological mixing events on the disease profile of the bat colony and subsequently on the dynamics of rabies viruses in bats. Our theoretical framework, which is based on individual (intra-host) models of the response of the host to a viral challenge and virus-specific disease mechanisms, integrates the individual components to provide information about the disease structure and the demographic composition of the bat colony. We focus on the changes in dynamics at the population level due to two processes: (1) immunological diversity in a biological process, reproduction, and (2) immunological diversity in a physical-physiological process, migration. The results suggest that immunotypic mixing plays a critical role in the disease progression within populations and it is an important factor in determining the persistence of rabies in exposed bat colonies.