Cadherin-related family member 3, a childhood asthma susceptibility gene product, mediates rhinovirus C binding and replication

The ICAM-1 ligand HRV-A89 is internalized independently of clathrin-mediated endocytosis and its capsid reaches late endosomes

The human rhinovirus (HRV) A2 is endocytosed by clathrin-mediated endocytosis (CME) bound to the classical LDL receptor and releases its RNA during its transport to late endosomes. Here it is shown that - presumably due to an effect on virus recycling - a low concentration of the CME inhibitor chlorpromazine present during virus internalization (30 min) did not reduce HRV-A2 infection, but strongly inhibited short-time (5 min) endocytosis of HRV-A2. Chlorpromazine had no effect on the colocalization of the ICAM-1 ligand HRV-A89 with early endosomes, excluding CME as the main endocytosis pathway of this virus. As published for HRV-A2 and HRV-A14, HRV-A89 partially colocalized with lysosome-associated membrane protein 2 and the microtubule inhibitor nocodazole did not reduce virus infection when present only during virus internalization. Together with previous work these data suggest that there are no principal differences between endocytosis pathways of ICAM-1-binding rhinoviruses in different cell types.

A four-part guide to lung immunology: Invasion, inflammation, immunity, and intervention

Lungs are important respiratory organs primarily involved in gas exchange. Lungs interact directly with the environment and their primary function is affected by several inflammatory responses caused by allergens, inflammatory mediators, and pathogens, eventually leading to disease. The immune architecture of the lung consists of an extensive network of innate immune cells, which induce adaptive immune responses based on the nature of the pathogen(s). The balance of immune responses is critical for maintaining immune homeostasis in the lung. Infection by pathogens and physical or genetic dysregulation of immune homeostasis result in inflammatory diseases. These responses culminate in the production of a plethora of cytokines such as TSLP, IL-9, IL-25, and IL-33, which have been implicated in the pathogenesis of several inflammatory and autoimmune diseases. Shifting the balance of Th1, Th2, Th9, and Th17 responses have been the targets of therapeutic interventions in the treatment of these diseases. Here, we have briefly reviewed the innate and adaptive i3mmune responses in the lung. Genetic and environmental factors, and infection are the major causes of dysregulation of various functions of the lung. We have elaborated on the impact of inflammatory and infectious diseases, advances in therapies, and drug delivery devices on this critical organ. Finally, we have provided a comprehensive compilation of different inflammatory and infectious diseases of the lungs and commented on the pros and cons of different inhalation devices for the management of lung diseases. The review is intended to provide a summary of the immunology of the lung, with an emphasis on drug and device development.

Rhinovirus—A True Respiratory Threat or a Common Inconvenience of Childhood?

A decade-long neglect of rhinovirus as an important agent of disease in humans was primarily due to the fact that they were seen as less virulent and capable of causing only mild respiratory infections such as common cold. However, with an advent of molecular diagnostic methods, an increasing number of reports placed them among the pathogens found in the lower respiratory tract and recognized them as important risk factors for asthma-related pathology in childhood. As the spread of rhinovirus was not severely affected by the implementation of social distancing and other measures during the coronavirus disease 2019 (COVID-19) pandemic, its putative pathogenic role has become even more evident in recent years. By concentrating on children as the most vulnerable group, in this narrative review we first present classification and main traits of rhinovirus, followed by epidemiology and clinical presentation, risk factors for severe forms of the disease, long-term complications and the pathogenesis of asthma, as well as a snapshot of treatment trials and studies. Recent evidence suggests that the rhinovirus is a significant contributor to respiratory illness in both high-risk and low-risk populations of children.

What Have Mechanistic Studies Taught Us About Childhood Asthma?

Childhood asthma is a chronic heterogeneous syndrome consisting of different disease entities or phenotypes. The immunologic and cellular processes that occur during asthma development are still not fully understood but represent distinct endotypes. Mechanistic studies have examined the role of gene expression, protein levels, and cell types in early life development and the manifestation of asthma, many under the influence of environmental stimuli, which can be both protective and risk factors for asthma. Genetic variants can regulate gene expression, controlled partly by different epigenetic mechanisms. In addition, environmental factors, such as living space, nutrition, and smoking, can contribute to these mechanisms. All of these factors produce modifications in gene expression that can alter the development and function of immune and epithelial cells and subsequently different trajectories of childhood asthma. These early changes in a partially immature immune system can have dramatic effects (e.g., causing dysregulation), which in turn contribute to different disease endotypes and may help to explain differential responsiveness to asthma treatment. In this review, we summarize published studies that have aimed to uncover distinct mechanisms in childhood asthma, considering genetics, epigenetics, and environment. Moreover, a discussion of new, powerful tools for single-cell immunologic assays for phenotypic and functional analysis is included, which promise new mechanistic insights into childhood asthma development and therapeutic and preventive strategies.

Heparin mimetics as potential intervention for COVID-19 and their bio-manufacturing

The COVID-19 pandemic has caused severe health problems worldwide and unprecedented decimation of the global economy. Moreover, after more than 2 years, many populations are still under pressure of infection. Thus, a broader perspective in developing antiviral strategies is still of great importance. Inspired by the observed multiple benefits of heparin in the treatment of thrombosis, the potential of low molecular weight heparin (LMWH) for the treatment of COVID-19 have been explored. Clinical applications found that LMWH decreased the level of inflammatory cytokines in COVID-19 patients, accordingly reducing lethality. Furthermore, several in vitro studies have demonstrated the important roles of heparan sulfate in SARS-CoV-2 infection and the inhibitory effects of heparin and heparin mimetics in viral infection. These clinical observations and designed studies argue for the potential to develop heparin mimetics as anti-SARS-CoV-2 drug candidates. In this review, we summarize the properties of heparin as an anticoagulant and the pharmaceutical possibilities for the treatment of virus infection, focusing on the perspectives of developing heparin mimetics via chemical synthesis, chemoenzymatic synthesis, and bioengineered production by microbial cell factories. The ultimate goal is to pave the eminent need for exploring novel compounds to treat coronavirus infection-caused diseases.

25 Years of translational research in the Copenhagen Prospective Studies on Asthma in Childhood (COPSAC)

The Copenhagen Prospective Studies on Asthma in Childhood (COPSAC) mother-child cohorts have provided a foundation of 25 years of research on the origins, prevention, and natural history of childhood asthma and related disorders. COPSAC's approach is characterized by clinical translational research with longitudinal deep phenotyping and exposure assessments from pregnancy, in combination with multi-omic data layers and embedded randomized controlled trials. One trial showed that fish oil supplementation during pregnancy prevented childhood asthma and identified pregnant women with the highest benefits from supplementation, thereby creating the potential for personalized prevention. COPSAC revealed that airway colonization with pathogenic bacteria in early life is associated with an increased risk of asthma. Further, airway bacteria were shown to be a trigger of acute asthma-like symptoms, with benefit from antibiotic treatment. COPSAC identified an immature gut microbiome in early life as a risk factor for asthma and allergy and further demonstrated that asthma can be predicted by infant lung function. At a molecular level, COPSAC has identified novel susceptibility genes, early immune deviations, and metabolomic alterations associated with childhood asthma. Thus, the COPSAC research program has enhanced our understanding of the processes causing childhood asthma and has suggested means of personalized prevention and treatment.

How the Competition for Cysteine May Promote Infection of SARS-CoV-2 by Triggering Oxidative Stress

SARS-CoV-2 induces a broad range of clinical manifestations. Besides the main receptor, ACE2, other putative receptors and co-receptors have been described and could become genuinely relevant to explain the different tropism manifested by new variants. In this study, we propose a biochemical model envisaging the competition for cysteine as a key mechanism promoting the infection and the selection of host receptors. The SARS-CoV-2 infection produces ROS and triggers a massive biosynthesis of proteins rich in cysteine; if this amino acid becomes limiting, glutathione levels are depleted and cannot control oxidative stress. Hence, infection succeeds. A receptor should be recognized as a marker of suitable intracellular conditions, namely the full availability of amino acids except for low cysteine. First, we carried out a comparative investigation of SARS-CoV-2 proteins and human ACE2. Then, using hierarchical cluster protein analysis, we searched for similarities between all human proteins and spike produced by the latest variant, Omicron BA.1. We found 32 human proteins very close to spike in terms of amino acid content. Most of these potential SARS-CoV-2 receptors have less cysteine than spike. We suggest that these proteins could signal an intracellular shortage of cysteine, predicting a burst of oxidative stress when used as viral entry mediators.

Altered cell function and increased replication of rhinoviruses and EV-D68 in airway epithelia of asthma patients

Introduction

Rhinovirus (RV) infections constitute one of the main triggers of asthma exacerbations and an important burden in pediatric yard. However, the mechanisms underlying this association remain poorly understood.

Methods

In the present study, we compared infections of in vitro reconstituted airway epithelia originating from asthmatic versus healthy donors with representative strains of RV-A major group and minor groups, RV-C, RV-B, and the respiratory enterovirus EV-D68.

Results

We found that viral replication was higher in tissues derived from asthmatic donors for all tested viruses. Viral receptor expression was comparable in non-infected tissues from both groups. After infection, ICAM1 and LDLR were upregulated, while CDHR3 was downregulated. Overall, these variations were related to viral replication levels. The presence of the CDHR3 asthma susceptibility allele (rs6967330) was not associated with increased RV-C replication. Regarding the tissue response, a significantly higher interferon (IFN) induction was demonstrated in infected tissues derived from asthmatic donors, which excludes a defect in IFN-response. Unbiased transcriptomic comparison of asthmatic versus control tissues revealed significant modifications, such as alterations of cilia structure and motility, in both infected and non-infected tissues. These observations were supported by a reduced mucociliary clearance and increased mucus secretion in non-infected tissues from asthmatic donors.

Discussion

Altogether, we demonstrated an increased permissiveness and susceptibility to RV and respiratory EV infections in HAE derived from asthmatic patients, which was associated with a global alteration in epithelial cell functions. These results unveil the mechanisms underlying the pathogenesis of asthma exacerbation and suggest interesting therapeutic targets.

The understanding of asthma pathogenesis in the era of precision medicine

Asthma is a syndrome with extremely diverse clinical phenotypes in which the onset, severity, and response to treatment are defined by the complex interplay of many genetic and environmental factors. Environmental factors epigenetically affect gene expression, and the disease is driven by a multidimensional dynamic network involving RNA and protein molecules derived from gene expression, as well as various metabolic products. In other words, specific pathophysiological mechanisms or endotypes are dynamic networks that arise in response to individual genotypes and the various environmental factors to which individuals have been exposed since before birth, such as diet, infection, air pollution, smoking, antibiotic use, and the bacterial flora of the intestinal tract, skin, and lungs. A key feature of asthma genome scans is their potential to reveal the molecular pathways that lead to pathogenesis. Endotypes that drive the disease have a significant impact on the phenotypes of asthma patients, including their drug responsiveness. Understanding endotypes will lead to not only the implementation of therapies that are tailored to the specific molecular network(s) underlying the patient's condition, but also to the development of therapeutic strategies that target individual endotypes, as well as to precision health, which will enable the prediction of disease onset with high accuracy from an early stage and the implementation of preventive strategies based on endotypes. Understanding of endotypes will pave the way for the practice of precision medicine in asthma care, moving away from 'one-size-fits-all' medicine and population-based prevention approaches that do not take individuals' susceptibility into account.

Asthma exacerbations: the Achilles heel of asthma care

Asthma exacerbations significantly impact millions of patients worldwide to pose large disease burdens on affected patients, families, and health-care systems. Although numerous environmental factors cause asthma exacerbations, viral respiratory infections are the principal triggers. Advances in the pathophysiology of asthma have elucidated dysregulated protective immune responses and upregulated inflammation that create susceptibility and risks for exacerbation. Biologics for the treatment of severe asthma reduce rates of exacerbations and identify specific pathways of inflammation that contribute to altered pathophysiology, novel therapeutic targets, and informative biomarkers. Major steps to prevent exacerbations include the identification of molecular pathways whose blockage will prevent asthma attacks safely, predictably, and effectively.

Respiratory illness virus infections with special emphasis on COVID-19

Viruses that emerge pose challenges for treatment options as their uniqueness would not know completely. Hence, many viruses are causing high morbidity and mortality for a long time. Despite large diversity, viruses share common characteristics for infection. At least 12 different respiratory-borne viruses are reported belonging to various virus taxonomic families. Many of these viruses multiply and cause damage to the upper and lower respiratory tracts. The description of these viruses in comparison with each other concerning their epidemiology, molecular characteristics, disease manifestations, diagnosis and treatment is lacking. Such information helps diagnose, differentiate, and formulate the control measures faster. The leading cause of acute illness worldwide is acute respiratory infections (ARIs) and are responsible for nearly 4 million deaths every year, mostly in young children and infants. Lower respiratory tract infections are the fourth most common cause of death globally, after non-infectious chronic conditions. This review aims to present the characteristics of different viruses causing respiratory infections, highlighting the uniqueness of SARS-CoV-2. We expect this review to help understand the similarities and differences among the closely related viruses causing respiratory infections and formulate specific preventive or control measures.

The Role of Viruses in the Inception of Chronic Rhinosinusitis

Chronic rhinosinusitis (CRS) is a complex inflammatory disorder that affects between 2% and 16% of adults in the United States, with estimated healthcare costs between 4 and 12 million USD. Viruses are a common etiologic factor for URIs, are frequently identified in the sinuses of patients with CRS, and trigger CRS exacerbations. Therefore, investigating the role of viruses provides an opportunity to identify their role in the pathogenesis of CRS. In this review, we identified the viruses frequently isolated in patients with CRS, as well as their associated immunologic responses and contributions to inflammation. Rhinovirus, parainfluenza virus, influenza virus, and respiratory syncytial virus are the viruses commonly found in patients with CRS. This information allows us to target pathways early in the pathogenesis of CRS, thereby playing a significant role in slowing the progression of this chronic disease.

Effects of COVID-19 and Social Distancing on Rhinovirus Infections and Asthma Exacerbations

Since their discovery in the 1950s, rhinoviruses (RVs) have been recognized as a major causative agent of the "common cold" and cold-like illnesses, accounting for more than 50% of upper respiratory tract infections. However, more than that, respiratory viral infections are responsible for approximately 50% of asthma exacerbations in adults and 80% in children. In addition to causing exacerbations of asthma, COPD and other chronic lung diseases, RVs have also been implicated in the pathogenesis of lower respiratory tract infections including bronchiolitis and community acquired pneumonia. Finally, early life respiratory viral infections with RV have been associated with asthma development in children. Due to the vast genetic diversity of RVs (approximately 160 known serotypes), recurrent infection is common. RV infections are generally acquired in the community with transmission occurring via inhalation of aerosols, respiratory droplets or fomites. Following the outbreak of coronavirus disease 2019 (COVID-19), exposure to RV and other respiratory viruses was significantly reduced due to social-distancing, restrictions on social gatherings, and increased hygiene protocols. In the present review, we summarize the impact of COVID-19 preventative measures on the incidence of RV infection and its sequelae.

Construction of a Vero Cell Line Expressing Human ICAM1 for the Development of Rhinovirus Vaccines

Human rhinoviruses (HRVs) are small non-enveloped RNA viruses that belong to the Enterovirus genus within the Picornaviridae family and are known for causing the common cold. Though symptoms are generally mild in healthy individuals, the economic burden associated with HRV infection is significant. A vaccine could prevent disease. The Vero-cell-based viral vaccine platform technology was considered for such vaccine development. Unfortunately, most HRV strains are unable to propagate on Vero cells due to a lack of the major receptor of HRV group A and B, intercellular adhesion molecule (ICAM1, also known as CD54). Therefore, stable human ICAM1 expressing Vero cell clones were generated by transfecting the ICAM1 gene in Vero cells and selecting clones that overexpressed ICAM1 on the cell surface. Cell banks were made and expression of ICAM1 was stable for at least 30 passages. The Vero_ICAM1 cells and parental Vero cells were infected with four HRV prototypes, B14, A16, B37 and A57. Replication of all four viruses was detected in Vero_ICAM1, but not in the parental Vero cells. Altogether, Vero cells expressing ICAM1 could efficiently propagate the tested HRV strains. Therefore, ICAM1-expressing cells could be a useful tool for the development and future production of polyvalent HRV vaccines or other viruses that use ICAM1 as a receptor.

Engineering the common cold to be a live-attenuated SARS-CoV-2 vaccine

According to the American Centers for Disease Control and Prevention, people in all age groups catch two or more “colds” per year, at least half of which are caused by human rhinoviruses. Despite decades of effort, there are no vaccines or drugs against rhinovirus infections and even social distancing measures that were effective in reducing the spread of the pandemic coronavirus, SARS-CoV-2, did not reduce the rate of rhinovirus detection. Fortunately, most rhinovirus strains are naturally attenuated in that they are not associated with serious illness, hospitalization or mortality. Instead, rhinoviruses are one of the most frequent viruses found in nasal swabs of asymptomatic, healthy people. Since rhinovirus infections cannot be avoided, a rational approach would be to engineer them for the benefit of their human hosts. Rhinovirus infections naturally induce robust mucosal and serum immune responses to all virus-expressed proteins. Several replication-competent, human rhinovirus vaccine vectors able to express protective antigens for other pathogens have already been designed and tested in animal models. With this strategy, the inevitable common cold would be able to induce immunity not just to a specific rhinovirus serotype but to other more pathogenic respiratory viruses as well. This article reviews existing rhinovirus vaccine vector technology and describes the characteristics that make live-attenuated rhinoviruses attractive vaccine candidates for SARS-CoV-2 and other pathogenic respiratory viruses in the future.

Viral infection and allergy status impact severity of asthma symptoms in children with asthma exacerbations

BACKGROUND

Although viral infection is known to be associated with asthma exacerbations, prior research has not identified reliable predictors of acute symptom severity in virus-related asthma exacerbations (VRAEs).

OBJECTIVE

To determine the effect of asthma control and viral infection on the severity of current illness and evaluate biomarkers related to acute symptoms during asthma exacerbations.

METHODS

We prospectively enrolled 120 children with physician-diagnosed asthma and current wheezing who presented to Arkansas Children's Hospital emergency department. The asthma control test (ACT) stratified controlled (ACT > 19) and uncontrolled (ACT ≤ 19) asthma, whereas pediatric respiratory symptom scores evaluated symptoms. Nasopharyngeal swabs were obtained for viral analysis, and inflammatory mediators were evaluated by nasal filter paper and Luminex assays.

RESULTS

There were 33 children with controlled asthma and 87 children with uncontrolled asthma. In those with uncontrolled asthma, 77% were infected with viruses during VRAE compared with 58% of those with controlled asthma. Uncontrolled subjects with VRAE had more acute symptoms compared with the controlled subjects with VRAE or uncontrolled subjects without a virus. The uncontrolled subjects with VRAE and allergy had the highest acute symptom scores (3.363 point pediatric respiratory symptom; P = .04). Children with asthma with higher symptom scores had more periostin (P = .02).

CONCLUSION

Detection of respiratory viruses is frequent in those with uncontrolled asthma. Uncontrolled subjects with viruses have more acute symptoms during exacerbations, especially in those with allergy. Periostin was highest in subjects with the most acute symptoms, regardless of control status. Taken together, these data imply synergy between viral infection and allergy in subjects with uncontrolled asthma when considering acute asthma symptoms and nasal inflammation during an exacerbation of asthma.

Viral Infection and Airway Epithelial Immunity in Asthma

Viral respiratory tract infections are associated with asthma development and exacerbation in children and adults. In the course of immune responses to viruses, airway epithelial cells are the initial platform of innate immunity against viral invasion. Patients with severe asthma are more vulnerable than those with mild to moderate asthma to viral infections. Furthermore, in most cases, asthmatic patients tend to produce lower levels of antiviral cytokines than healthy subjects, such as interferons produced from immune effector cells and airway epithelial cells. The epithelial inflammasome appears to contribute to asthma exacerbation through overactivation, leading to self-damage, despite its naturally protective role against infectious pathogens. Given the mixed and complex immune responses in viral-infection-induced asthma exacerbation, this review examines the diverse roles of airway epithelial immunity and related potential therapeutic targets and discusses the mechanisms underlying the heterogeneous manifestations of asthma exacerbations.

Human Rhinoviruses in Pediatric Patients in a Tertiary Care Hospital in Germany: Molecular Epidemiology and Clinical Significance

Rhinoviruses (RVs) constitute a substantial public health burden. To evaluate their abundance and genetic diversity in pediatric patients, RV RNA in respiratory samples was assessed using real-time RT-PCR and partial nucleic acid sequencing of viral genomes. Additionally, clinical data were retrieved from patient charts to determine the clinical significance of pediatric RV infections. In total, the respiratory specimens of 776 patients (<18 years), collected from 2013 to 2017, were analyzed. Infections occurred throughout the entire year, with peaks occurring in fall and winter, and showed remarkably high intra- and interseasonal diversity for RV genotypes. RV species were detected in the following frequencies: 49.1% RV-A, 5.9% RV-B, and 43.6% RV-C. RV-C was found to be more frequently associated with asthma (p = 0.04) and bronchiolitis (p < 0.001), while RV-A was more frequently associated with fever (p = 0.001) and pneumonia (p = 0.002). Additionally, 35.3% of the patients had co-infections with other pathogens, which were associated with a longer hospital stay (p < 0.001), need for ventilation (p < 0.001), and pneumonia (p < 0.001). Taken together, this study shows pronounced RV genetic diversity in pediatric patients and indicates differences in RV-associated pathologies, as well as an important role for co-infections.

Innate Immune Responses by Respiratory Viruses, Including Rhinovirus, During Asthma Exacerbation

Viral infection, especially with rhinovirus (RV), is a major cause of asthma exacerbation. The production of anti-viral cytokines such as interferon (IFN)-β and IFN-α from epithelial cells or dendritic cells is lower in patients with asthma or those with high IgE, which can contribute to viral-induced exacerbated disease in these patients. As for virus-related factors, RV species C (RV-C) induces more exacerbated disease than other RVs, including RV-B. Neutrophils activated by viral infection can induce eosinophilic airway inflammation through different mechanisms. Furthermore, virus-induced or virus-related proteins can directly activate eosinophils. For example, CXCL10, which is upregulated during viral infection, activates eosinophils in vitro. The role of innate immune responses, especially type-2 innate lymphoid cells (ILC2) and epithelial cell-related cytokines including IL-33, IL-25, and thymic stromal lymphopoietin (TSLP), in the development of viral-induced airway inflammation has recently been established. For example, RV infection induces the expression of IL-33 or IL-25, or increases the ratio of ILC2 in the asthmatic airway, which is correlated with the severity of exacerbation. A mouse model has further demonstrated that virus-induced mucous metaplasia and ILC2 expansion are suppressed by antagonizing or deleting IL-33, IL-25, or TSLP. For treatment, IFNs including IFN-β suppress not only viral replication but also ILC2 activation in vitro. Agonists of toll-like receptor (TLR) 3 or 7 can induce IFNs, which can then suppress viral replication and ILC2 activation. Therefore, if delivered in the airway, IFNs or TLR agonists could become innovative treatments for virus-induced asthma exacerbation.

Asthma and the Missing Heritability Problem: Necessity for Multiomics Approaches in Determining Accurate Risk Profiles

Asthma is ranked among the most common chronic conditions and has become a significant public health issue due to the recent and rapid increase in its prevalence. Investigations into the underlying genetic factors predict a heritable component for its incidence, estimated between 35% and 90% of causation. Despite the application of large-scale genome-wide association studies (GWAS) and admixture mapping approaches, the proportion of variants identified accounts for less than 15% of the observed heritability of the disease. The discrepancy between the predicted heritable component of disease and the proportion of heritability mapped to the currently identified susceptibility loci has been termed the ‘missing heritability problem.’ Here, we examine recent studies involving both the analysis of genetically encoded features that contribute to asthma and also the role of non-encoded heritable characteristics, including epigenetic, environmental, and developmental aspects of disease. The importance of vertical maternal microbiome transfer and the influence of maternal immune factors on fetal conditioning in the inheritance of disease are also discussed. In order to highlight the broad array of biological inputs that contribute to the sum of heritable risk factors associated with allergic disease incidence that, together, contribute to the induction of a pro-atopic state. Currently, there is a need to develop in-depth models of asthma risk factors to overcome the limitations encountered in the interpretation of GWAS results in isolation, which have resulted in the missing heritability problem. Hence, multiomics analyses need to be established considering genetic, epigenetic, and functional data to create a true systems biology-based approach for analyzing the regulatory pathways that underlie the inheritance of asthma and to develop accurate risk profiles for disease.

A Pandemic Lesson for Global Lung Diseases: Exacerbations Are Preventable

A dramatic global reduction in the incidence of common seasonal respiratory viral infections has resulted from measures to limit the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) during the pandemic. This has been accompanied by falls reaching 50% internationally in the incidence of acute exacerbations of preexisting chronic respiratory diseases that include asthma, chronic obstructive pulmonary disease, and cystic fibrosis. At the same time, the incidence of acute bacterial pneumonia and sepsis has fallen steeply worldwide. Such findings demonstrate the profound impact of common respiratory viruses on the course of these global illnesses. Reduced transmission of common respiratory bacterial pathogens and their interactions with viruses appear also as central factors. This review summarizes pandemic changes in exacerbation rates of asthma, chronic obstructive pulmonary disease, cystic fibrosis, and pneumonia. We draw attention to the substantial body of knowledge about respiratory virus infections in these conditions, and that it has not yet translated into clinical practice. Now that the large scale of benefits that could be gained by managing these pathogens is unmistakable, we suggest that the field merits substantial academic and industrial investment. We consider how pandemic-inspired measures for prevention and treatment of common infections should become a cornerstone for managing respiratory diseases.

Gene polymorphisms in asthma: a narrative review

Background and Objective

Asthma is a heterogeneous disease caused by interactions between genetic and environmental factors. Genome-wide association studies (GWAS) have revealed that genetic variation plays a crucial role in the occurrence and development of asthma. The objective is to systematically review the existing literature on the association between gene polymorphisms and asthma to better understand the relationship between genetic factors and the occurrence and development of asthma.

Methods

We used keywords "asthma" and "gene polymorphism" with their combinations to search for relevant literature published from 2000 to 2021 in the PubMed database and the foreign medical literature retrieval service (FMRS). All articles included in the review are English. Then, we summarized the information pertaining to the genetic factors related to asthma susceptibility.

Key Content and Findings

This study summarized the information on 10 gene variants related to the risk of asthma published over the past 20 years, which will assist in further understanding the role of genetic variants in the risk of asthma.

Conclusion

Dozens of candidate genes have been identified that were associated with asthma risk. Asthmatics existed specific gene variation performed different response to therapy. Personalized therapy based on genotypic profiling would be an important direction in the future. However, it remains a great challenge for us to explore the relationship between gene polymorphisms and pathophysiological mechanism of asthma.

Identification of Epitopes on Rhinovirus 89 Capsid Proteins Capable of Inducing Neutralizing Antibodies

Rhinoviruses (RVs) are major causes of the common cold, but they can also trigger exacerbations of asthma. More than 160 different RV strains exist and can be classified into three genetic species (RV-A, RV-B and RV-C) which bind to different receptors on human cells including intracellular adhesion molecule 1 (ICAM-1), the low-density lipoprotein receptor (LDLR) or the cadherin-related family member 3 (CDHR3). Epitopes located in the RV capsid have mainly been determined for RV2, a minor-group RV-A strain binding to LDLR, and for RV14, a major-group RV-B strain binding to ICAM-1. In order to study epitopes involved in the neutralization of RV89, an ICAM-1-binding RV-A strain which is highly different from RV2 and RV14 in terms of receptor specificity and sequence, respectively, we analyzed the specificity and epitopes of a highly neutralizing antiserum using recombinantly produced RV89 capsid proteins (VP1, VP2, VP3 and VP4), recombinant fragments and synthetic overlapping peptides thereof. We found that the antiserum which neutralized in vitro RV89 infection up to a dilution of 1:24,000 reacted with the capsid proteins VP1 and VP2 but not with VP3 and VP4. The neutralizing antibodies recognized recombinant fragments comprising approximately 100 amino acids of the N- and C-terminus of VP1 and the middle part of VP2, in particular, three peptides which, according to molecular modeling based on the three-dimensional structure of RV16, were surface-exposed on the viral capsid. Two recombinant fusion proteins containing the identified peptides fused to hepatitis B (HBV)-derived preS as a carrier protein induced upon immunization of rabbits antibodies capable of neutralizing in vitro RV89 infections. Interestingly, the virus-neutralizing epitopes determined for RV89 corresponded to those determined for minor-group RV2 binding to LDL and major-group RV14 belonging to the RV-B species, which are highly different from RV89. Our results indicate that highly different RV strains, even when reacting with different receptors, seem to engage similar parts of their capsid in the infection process. These results may be important for the design of active and passive immunization strategies for RV.

Impact of Therapeutics on Unified Immunity During Allergic Asthma and Respiratory Infections

Asthma is a common chronic respiratory disease that affects millions of people worldwide. Patients with allergic asthma, the most prevalent asthma endotype, are widely considered to possess a defective immune response against some respiratory infectious agents, including viruses, bacteria and fungi. Furthermore, respiratory pathogens are associated with asthma development and exacerbations. However, growing data suggest that the immune milieu in allergic asthma may be beneficial during certain respiratory infections. Immunomodulatory asthma treatments, although beneficial, should then be carefully prescribed to avoid misuse and overuse as they can also alter the host microbiome. In this review, we summarize and discuss recent evidence of the correlations between allergic asthma and the most significant respiratory infectious agents that have a role in asthma pathogenesis. We also discuss the implications of current asthma therapeutics beyond symptom prevention.

Targeting intercellular adhesion molecule-1 (ICAM-1) to reduce rhinovirus-induced acute exacerbations in chronic respiratory diseases

The chronic respiratory non-communicable diseases, asthma and chronic obstructive pulmonary disease (COPD) are among the leading causes of global mortality and morbidity. Individuals suffering from these diseases are particularly susceptible to respiratory infections caused by bacterial and/or viral pathogens, which frequently result in exacerbation of symptoms, lung function decline, frequent hospital emergency visits and increased socioeconomic burden. Human rhinoviruses (HRV) remain the major viral pathogen group implicated in exacerbations of both asthma and COPD. The rhinoviral entry into the host lung epithelium is facilitated primarily by the adhesion site (“receptor”) intercellular adhesion molecule-1 (ICAM-1), coincidentally expressed on the respiratory epithelium in these conditions. Multiple observations of increased airway ICAM-1 protein in asthmatics, smokers and smoking-related COPD have been recorded in the literature. However, the lack of robust therapies for COPD in particular has triggered a renewed interest in assessing receptor antagonism-based anti-viral strategies for treatment of intercurrent viral infections in those with pre-existing chronic lung diseases. Given the crucial role ICAM-1 plays in facilitating HRV adhesion and, thus, transmissibility to the host respiratory system, as well as the up-regulation of ICAM-1 by smoking, we summarize the role of HRV in smoking-induced COPD and especially highlight the role of ICAM-1 in epithelial viral adhesion and chronic lung disease progression. Further, the review also sheds light specifically on evolving precision therapeutic strategies in blocking ICAM-1 for preventing viral adhesion and exacerbations of COPD.

Human rhinoviruses prevailed among children in the setting of wearing face masks in Shanghai, 2020

Background

Human rhinovirus (HRV) is the predominant etiological agent of the common cold in children and adults. A recent study showed that the inhibitory effect of face masks on viral shedding of HRV was less prominent than that on other respiratory viruses. Considering that most Chinese people have worn face masks in public area since the outbreak of coronavirus disease 2019, we aimed to find out whether HRV prevailed among children in 2020 and demonstrate the details of the epidemiological features of HRV under such a special circumstance.

Methods

We summarized the incidences of various respiratory virus infections in patients who visited the Children’s Hospital of Fudan University during 2018–2020, and genotyped HRV positive nasopharyngeal specimens collected from 316 inpatients and 72 outpatients that visited the hospital in 2020.

Results

There was a major prevalence of HRV among children in the latter half of 2020, with a clear seasonality that HRV-As prevailed in summer while HRV-Cs in autumn. HRV-As were more prone to cause severe lower respiratory tract infections (LRTI), while HRV-Cs were closely associated with childhood wheezing. The predominant genotypes were A11, A28, A47, A82, A101, C40 and C43. Notably, A21, A82 and A101 took up larger proportions in severe cases than in non-severe cases.

Conclusions

Our findings described a major prevalence of HRVs among children in 2020, which highlight the unique transmitting pattern of HRV and help to narrow the targets for antiviral strategies.

Rhinovirus Infections and Their Roles in Asthma: Etiology and Exacerbations

Rhinovirus infections can cause wheezing illnesses in all age groups. In preschool children, rhinovirus infections frequently initiate acute wheezing illnesses. Children who wheeze with rhinoviruses are at increased risk to go on to develop asthma. Once asthma is established, rhinovirus infections are potent triggers for acute airway obstruction and exacerbations in children and adults. Paradoxically, for most individuals, rhinovirus infections commonly cause cold symptoms with little or no involvement of the lower airways. This paradox has led investigators to identify specific risk factors and mechanisms for rhinovirus wheezing, and this review will outline progress in 3 main areas. First, the 3 species of rhinoviruses have different patterns of infection and virulence. Second, personal factors such as lung function and immunity influence lower respiratory outcomes of rhinovirus infection. The mucosal immune response is critical, and the quality of the interferon response and allergic inflammation interacts to determine the risk for rhinovirus wheezing. Finally, rhinovirus infections can promote pathogen-dominated airway microbiota that increase the risk for wheezing. Although specific antivirals for rhinovirus are still not available, identifying risk factors for wheezing illnesses has provided several other potential targets and strategies for reducing the risk of rhinovirus-induced wheezing and exacerbations of asthma.

Immunoglobulin E-Dependent Activation of Immune Cells in Rhinovirus-Induced Asthma Exacerbation

Acute exacerbation is the major cause of asthma morbidity, mortality, and health-care costs. Respiratory viral infections, particularly rhinovirus (RV) infections, are associated with the majority of asthma exacerbations. The risk for bronchoconstriction with RV is associated with allergic sensitization and type 2 airway inflammation. The efficacy of the humanized anti-IgE monoclonal antibody omalizumab in treating asthma and reducing the frequency and severity of RV-induced asthma exacerbation is well-known. Despite these clinical data, mechanistic details of omalizumab's effects on RV-induced asthma exacerbation have not been well-defined for years due to the lack of appropriate animal models. In this Perspective, we discuss potential IgE-dependent roles of mast cells and dendritic cells in asthma exacerbations.

Chemical Evolution of Rhinovirus Identifies Capsid-Destabilizing Mutations Driving Low-pH-Independent Genome Uncoating

Rhinoviruses (RVs) cause recurrent infections of the nasal and pulmonary tracts, life-threatening conditions in chronic respiratory illness patients, predisposition of children to asthmatic exacerbation, and large economic cost. RVs are difficult to treat. They rapidly evolve resistance and are genetically diverse. Here, we provide insight into RV drug resistance mechanisms against chemical compounds neutralizing low pH in endolysosomes. Serial passaging of RV-A16 in the presence of the vacuolar proton ATPase inhibitor bafilomycin A1 (BafA1) or the endolysosomotropic agent ammonium chloride (NH4Cl) promoted the emergence of resistant virus populations. We found two reproducible point mutations in viral proteins 1 and 3 (VP1 and VP3), A2526G (serine 66 to asparagine [S66N]), and G2274U (cysteine 220 to phenylalanine [C220F]), respectively. Both mutations conferred cross-resistance to BafA1, NH4Cl, and the protonophore niclosamide, as identified by massive parallel sequencing and reverse genetics, but not the double mutation, which we could not rescue. Both VP1-S66 and VP3-C220 locate at the interprotomeric face, and their mutations increase the sensitivity of virions to low pH, elevated temperature, and soluble intercellular adhesion molecule 1 receptor. These results indicate that the ability of RV to uncoat at low endosomal pH confers virion resistance to extracellular stress. The data endorse endosomal acidification inhibitors as a viable strategy against RVs, especially if inhibitors are directly applied to the airways. IMPORTANCE Rhinoviruses (RVs) are the predominant agents causing the common cold. Anti-RV drugs and vaccines are not available, largely due to rapid evolutionary adaptation of RVs giving rise to resistant mutants and an immense diversity of antigens in more than 160 different RV types. In this study, we obtained insight into the cell biology of RVs by harnessing the ability of RVs to evolve resistance against host-targeting small chemical compounds neutralizing endosomal pH, an important cue for uncoating of normal RVs. We show that RVs grown in cells treated with inhibitors of endolysosomal acidification evolved capsid mutations yielding reduced virion stability against elevated temperature, low pH, and incubation with recombinant soluble receptor fragments. This fitness cost makes it unlikely that RV mutants adapted to neutral pH become prevalent in nature. The data support the concept of host-directed drug development against respiratory viruses in general, notably at low risk of gain-of-function mutations.

Susceptibility to rhinovirus-induced early wheezing as a risk factor for subsequent asthma development

Abstract:

Rhinovirus is one of the two most common viral agents that cause bronchiolitis in young children. During the first 12 months, it is second to the respiratory syncytial virus, but after 12 months, it begins dominating the statistics. Wheezing and dry cough are typical clinical symptoms indicative of rhinovirus-induced bronchiolitis, although overlap of symptoms with other virus infections is common. Several studies have shown that atopic predisposition and reduced interferon responses increase susceptibility to rhinovirus-induced wheezing. More recent studies have found that certain genetic variations at strong asthma loci also increase susceptibility. Rhinovirus-induced wheezing in the early years of life is known to increase the risk of subsequent asthma development and may be associated with airway remodeling. This risk is increased by aeroallergen sensitization. Currently, there are no clinically approved preventive treatments for asthma. However, studies show promising results indicating that children with rhinovirus-affected first-time wheezing respond to bronchodilators in terms of less short-term symptoms and that controlling airway inflammatory responses with anti-inflammatory medication may markedly decrease asthma development. Also, enhancing resistance to respiratory viruses has been a topic of discussion. Primary and secondary prevention strategies are being developed with the aim of decreasing the incidence of asthma. Here, we review the current knowledge on rhinovirus-induced early wheezing as a risk factor for subsequent asthma development and related asthma-prevention strategies.

Is there still evolution in the human population?

It is often claimed that humanity has stopped evolving because modern medicine erased all selection on survival. Even if that would be true, and it is not, there would be other mechanisms of evolution which could still led to changes in allelic frequencies. Here I show, by applying basic evolutionary genetics knowledge, that we expect humanity to evolve. The results from genome sequencing projects have repeatedly affirmed that there are still recent signs of selection in our genomes. I give some examples of such adaptation. Then I briefly discuss what our evolutionary future has in store for us.

Rhinovirus C replication is associated with the endoplasmic reticulum and triggers cytopathic effects in an in vitro model of human airway epithelium

The clinical impact of rhinovirus C (RV-C) is well-documented; yet, the viral life cycle remains poorly defined. Thus, we characterized RV-C15 replication at the single-cell level and its impact on the human airway epithelium (HAE) using a physiologically-relevant in vitro model. RV-C15 replication was restricted to ciliated cells where viral RNA levels peaked at 12 hours post-infection (hpi), correlating with elevated titers in the apical compartment at 24hpi. Notably, infection was associated with a loss of polarized expression of the RV-C receptor, cadherin-related family member 3. Visualization of double-stranded RNA (dsRNA) during RV-C15 replication revealed two distinct replication complex arrangements within the cell, likely corresponding to different time points in infection. To further define RV-C15 replication sites, we analyzed the expression and colocalization of giantin, phosphatidylinositol-4-phosphate, and calnexin with dsRNA. Despite observing Golgi fragmentation by immunofluorescence during RV-C15 infection as previously reported for other RVs, a high ratio of calnexin-dsRNA colocalization implicated the endoplasmic reticulum as the primary site for RV-C15 replication in HAE. RV-C15 infection was also associated with elevated stimulator of interferon genes (STING) expression and the induction of incomplete autophagy, a mechanism used by other RVs to facilitate non-lytic release of progeny virions. Notably, genetic depletion of STING in HAE attenuated RV-C15 and -A16 (but not -B14) replication, corroborating a previously proposed proviral role for STING in some RV infections. Finally, RV-C15 infection resulted in a temporary loss in epithelial barrier integrity and the translocation of tight junction proteins while a reduction in mucociliary clearance indicated cytopathic effects on epithelial function. Together, our findings identify both shared and unique features of RV-C replication compared to related rhinoviruses and define the impact of RV-C on both epithelial cell organization and tissue functionality–aspects of infection that may contribute to pathogenesis in vivo.

Rhinovirus C has a global distribution and significant clinical impact–especially in those with underlying lung disease. Although RV-C is genetically, structurally, and biologically distinct from RV-A and -B viruses, our understanding of the RV-C life cycle has been largely inferred from these and other related viruses. Here, we performed a detailed analysis of RV-C15 replication in a physiologically-relevant model of human airway epithelium. Our single-cell, microscopy-based approach revealed that–unlike other RVs–the endoplasmic reticulum is the primary site for RV-C15 replication. RV-C15 replication also stimulated STING expression, which was proviral, and triggered dramatic changes in cellular organization, including altered virus receptor distribution, fragmented Golgi stacks, and the induction of incomplete autophagy. Additionally, we observed a loss of epithelial barrier function and a decrease in mucociliary clearance, a major defense mechanism in the lung, during RV-C15 infection. Together, these data reveal novel insight into RV-C15 replication dynamics and resulting cytopathic effects in the primary target cells for infection, thereby furthering our understanding of the pathogenesis of RV-C. Our work highlights similar, as well as unique, aspects of RV-C15 replication compared to related pathogens, which will help guide future studies on the molecular mechanisms of RV-C infection.

Considering biomarkers in asthma disease severity

Amongst patients with asthma, reliance on the type/dose of prescribed medication and symptom control does not adequately capture those at risk of adverse outcomes, and we need biomarkers for risk and treatment stratification which are consistently accurate, readily quantifiable and reproducible. The majority of patients with severe asthma, regardless of age, have predominant type-2 (T2) inflammation mediated disease, making airway/blood eosinophils, FeNO, periostin and/or allergic sensitization potentially important biomarkers for severe disease. In both adult and pediatric asthma, there is scope to improve prediction of severe attacks by using a composite T2 biomarkers of blood eosinophils and FeNO. Technological advances in component-resolved diagnostics (CRD) microarray technologies coupled with the development of interpretation software offer a possibility to use CRD as biomarkers of asthma severity amongst sensitized asthmatics. Genetic predisposition and polygenic risk scores of relevant traits (e.g., lung function, host immune responses, biomarkers of exposure from the indoor and outdoor environment, infection and microbial dysbiosis) may also contribute to prediction algorithms. We challenge the idea that asthma can be accurately defined in an individual patient by a discrete and static "endotype" (e.g., T2-high asthma). As we traverse the new era of molecular endotyping in asthma, we need to understand how relevant mechanisms impact patient outcomes, and in parallel develop new tools and approaches to stratify therapies and define individual patient trajectories.

Viral Induced Effects on a Vulnerable Epithelium; Lessons Learned From Paediatric Asthma and Eosinophilic Oesophagitis

The epithelium is integral to the protection of many different biological systems and for the maintenance of biochemical homeostasis. Emerging evidence suggests that particular children have epithelial vulnerabilities leading to dysregulated barrier function and integrity, that resultantly contributes to disease pathogenesis. These epithelial vulnerabilities likely develop in utero or in early life due to various genetic, epigenetic and environmental factors. Although various epithelia are uniquely structured with specific function, prevalent allergic-type epithelial diseases in children potentially have common or parallel disease processes. These include inflammation and immune response dysregulation stemming from atypical epithelial barrier function and integrity. Two diseases where aetiology and pathogenesis are potentially linked to epithelial vulnerabilities include Paediatric Asthma and Eosinophilic Oesophagitis (EoE). For example, rhinovirus C (RV-C) is a known risk factor for paediatric asthma development and is known to disrupt respiratory epithelial barrier function causing acute inflammation. In addition, EoE, a prevalent atopic condition of the oesophageal epithelium, is characterised by similar innate immune and epithelial responses to viral injury. This review examines the current literature and identifies the gaps in the field defining viral-induced effects on a vulnerable respiratory epithelium and resulting chronic inflammation, drawing from knowledge generated in acute wheezing illness, paediatric asthma and EoE. Besides highlighting the importance of epithelial structure and barrier function in allergic disease pathogenesis regardless of specific epithelial sub-types, this review focuses on the importance of examining other parallel allergic-type disease processes that may uncover commonalities driving disease pathogenesis. This in turn may be beneficial in the development of common therapeutics for current clinical management and disease prevention in the future.

Personal Network Inference Unveils Heterogeneous Immune Response Patterns to Viral Infection in Children with Acute Wheezing

Human rhinovirus (RV)-induced exacerbations of asthma and wheeze are a major cause of emergency room presentations and hospital admissions among children. Previous studies have shown that immune response patterns during these exacerbations are heterogeneous and are characterized by the presence or absence of robust interferon responses. Molecular phenotypes of asthma are usually identified by cluster analysis of gene expression levels. This approach however is limited, since genes do not exist in isolation, but rather work together in networks. Here, we employed personal network inference to characterize exacerbation response patterns and unveil molecular phenotypes based on variations in network structure. We found that personal gene network patterns were dominated by two major network structures, consisting of interferon-response versus FCER1G-associated networks. Cluster analysis of these structures divided children into subgroups, differing in the prevalence of atopy but not RV species. These network structures were also observed in an independent cohort of children with virus-induced asthma exacerbations sampled over a time course, where we showed that the FCER1G-associated networks were mainly observed at late time points (days four-six) during the acute illness. The ratio of interferon- and FCER1G-associated gene network responses was able to predict recurrence, with low interferon being associated with increased risk of readmission. These findings demonstrate the applicability of personal network inference for biomarker discovery and therapeutic target identification in the context of acute asthma which focuses on variations in network structure.

The GSDMB rs7216389 SNP is associated with chronic rhinosinusitis in a multi-institutional cohort

BACKGROUND

Chronic rhinosinusitis (CRS) is a multifactorial disease with a high co-occurrence with asthma. In this multicohort study, we tested whether single nucleotide polymorphisms (SNPs) associated with childhood asthma and rhinovirus (RV)-associated disease are related to an increased susceptibility to adult CRS in a multicohort retrospective case-control study.

METHODS

Participants at two tertiary academic rhinology centers, University of Arizona (UofA) and University of Pennsylvania (UPenn) were recruited. Cases were defined as those with physician diagnosed CRS (UofA, n = 149; UPenn, n = 250), and healthy controls were those without CRS (UofA, n = 66; UPenn, n = 275). Genomic DNA was screened for the GSDMB rs7216389 SNP and CDHR3 rs6967330 SNP. Gene dosage, or the number of combined risk alleles in a single subject was calculated. Meta-analysis of the association between GSDMB or CDHR3 genotypes and CRS was performed and additive gene dosage effect for each population calculated using p for trend.

RESULTS

A meta-analysis revealed a combined increased risk for CRS in subjects with the GSDMB rs7216389 SNP (odds ratio [OR] 1.40; 95% confidence interval [CI], 1.16-1.76; p = 0.004). Both the UofA (OR 1.73; 95% CI, 1.23-2.43; p = 0.002) and UPenn (OR 1.27; 95% CI, 1.02-1.58; p = 0.035) populations showed a significant positive association between the number of combined risk alleles of GSDMB rs7216389 SNP and CDHR3 rs6967330 SNP and risk for CRS.

CONCLUSION

Carriers of the GSDMB rs7216389 SNP and CDHR3 rs6967330 SNP are at increased susceptibility for CRS. These data suggest that therapeutic approaches to target aberrant responses to RV infection may play a role in the treatment of unified airway disease.

Human rhinovirus serotypes induces different immune responses

Background

Different species of human rhinovirus (HRV) can induce varied antiviral and inflammatory responses in human blood macrophages and lower airway epithelium. Although human nasal epithelial cells (HNECs) are a primary infection route of HRV, differences between major and minor groups of HRV in the upper airway epithelium have not been studied in detail. In this study, we investigated viral replications and immune responses of major and minor groups of HRV in the HNECs.

Methods

Viral replication, immune responses of IFN-β, IFN-λ, proinflammatory cytokines, and viral receptors, and mRNA expression of transcription factors of HRV16 (major group) and HRV1B (minor group) in the HNECs were assessed.

Results

Compared with HRV16, HRV1B replicated more actively without excessive cell death and produced higher IFN-β, IFN-λ1/3, CXCL10, IL-6, IL-8, and IL-18 levels. Furthermore, low-density lipoprotein receptor (LDLR), TLR3, MDA5, NF-κB, STAT1, and STAT2 mRNA levels increased in HRV1B-infected HNECs.

Conclusion

HRV1B induces a stronger antiviral and inflammatory response from cell entry to downstream signaling compared with HRV16.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12985-021-01701-1.

Deficient inflammasome activation permits an exaggerated asthma phenotype in rhinovirus C-infected immature mice

Compared to other RV species, RV-C has been associated with more severe respiratory illness and is more likely to occur in children with a history of asthma or who develop asthma. We therefore inoculated 6-day-old mice with sham, RV-A1B, or RV-C15. Inflammasome priming and activation were assessed, and selected mice treated with recombinant IL-1β. Compared to RV-A1B infection, RV-C15 infection induced an exaggerated asthma phenotype, with increased mRNA expression of Il5, Il13, Il25, Il33, Muc5ac, Muc5b, and Clca1; increased lung lineage-negative CD25+CD127+ST2+ ILC2s; increased mucous metaplasia; and increased airway responsiveness. Lung vRNA, induction of pro-inflammatory type 1 cytokines, and inflammasome priming (pro-IL-1β and NLRP3) were not different between the two viruses. However, inflammasome activation (mature IL-1β and caspase-1 p12) was reduced in RV-C15-infected mice compared to RV-A1B-infected mice. A similar deficiency was found in cultured macrophages. Finally, IL-1β treatment decreased RV-C-induced type 2 cytokine and mucus-related gene expression, ILC2s, mucous metaplasia, and airway responsiveness but not lung vRNA level. We conclude that RV-C induces an enhanced asthma phenotype in immature mice. Compared to RV-A, RV-C-induced macrophage inflammasome activation and IL-1β are deficient, permitting exaggerated type 2 inflammation and mucous metaplasia.

The role of CDHR3 in susceptibility to otitis media

Otitis media (OM) is common in young children and can cause hearing loss and speech, language, and developmental delays. OM has high heritability; however, little is known about OM-related molecular and genetic processes. CDHR3 was previously identified as a locus for OM susceptibility, but to date, studies have focused on how the CDHR3 p.Cys529Tyr variant increases epithelial binding of rhinovirus-C and risk for lung or sinus pathology. In order to further delineate a role for CDHR3 in OM, we performed the following: exome sequencing using DNA samples from OM-affected individuals from 257 multi-ethnic families; Sanger sequencing, logistic regression and transmission disequilibrium tests for 407 US trios or probands with OM; 16S rRNA sequencing and analysis for middle ear and nasopharyngeal samples; and single-cell RNA sequencing and differential expression analyses for mouse middle ear. From exome sequence data, we identified a novel pathogenic CDHR3 splice variant that co-segregates with OM in US and Finnish families. Additionally, a frameshift and six missense rare or low-frequency variants were identified in Finnish probands. In US probands, the CDHR3 p.Cys529Tyr variant was associated with the absence of middle ear fluid at surgery and also with increased relative abundance of Lysobacter in the nasopharynx and Streptomyces in the middle ear. Consistent with published data on airway epithelial cells and our RNA-sequence data from human middle ear tissues, Cdhr3 expression is restricted to ciliated epithelial cells of the middle ear and is downregulated after acute OM. Overall, these findings suggest a critical role for CDHR3 in OM susceptibility. KEY MESSAGES: • Novel rare or low-frequency CDHR3 variants putatively confer risk for otitis media. • Pathogenic variant CDHR3 c.1653 + 3G > A was found in nine families with otitis media. • CDHR3 p.Cys529Tyr was associated with lack of effusion and bacterial otopathogens. • Cdhr3 expression was limited to ciliated epithelial cells in mouse middle ear. • Cdhr3 was downregulated 3 h after infection of mouse middle ear.

The proton ATPase inhibitor bafilomycin A1 reduces the release of rhinovirus C and cytokines from primary cultures of human nasal epithelial cells

Rhinovirus species C (RV-C) causes more severe asthma attacks than other rhinovirus species. However, the modulation of RV-C replication by drugs has not been well studied. Primary human nasal epithelial (HNE) cells cultured on filter membranes with air-liquid interface methods were infected with RV-C03, and the levels of RV-C03 RNA collected from the airway surface liquid (ASL) of HNE cells were measured with a SYBR Green assay. Pretreatment of HNE cells with the specific vacuolar H⁺-ATPase inhibitor bafilomycin A₁ reduced the RV-C03 RNA levels in the ASL; inflammatory cytokines, including interleukin (IL)-1β, IL-6 and IL-8, in the supernatant; the mRNA expression of the RV-C receptor cadherin-related family member 3 (CDHR3) in the cells; and the number of acidic endosomes where RV-B RNA enters the cytoplasm. The levels of RV-C03 RNA in the ASL obtained from HNE cells with the CDHR3 rs6967,330 G/A genotype tended to be higher than those obtained from HNE cells with the G/G genotype. Pretreatment with the Na⁺/H⁺ exchanger inhibitor ethyl-isopropyl amiloride or either of the macrolides clarithromycin or EM900 also reduced RV-C03 RNA levels in the ASL and the number of acidic endosomes in HNE cells. In addition, significant levels of RV-A16, RV-B14 and RV-C25 RNA were detected in the ASL, and bafilomycin A₁ also decreased the RV-C25 RNA levels. These findings suggest that bafilomycin A₁ may reduce the release of RV-Cs and inflammatory cytokines from human airway epithelial cells. RV-Cs may be sensitive to drugs, including bafilomycin A₁, that increase endosomal pH, and CDHR3 may mediate virus entry through receptor-mediated endocytosis in human airway epithelial cells.

Defining Age-specific Relationships of Respiratory Syncytial Virus and Rhinovirus Species in Hospitalized Children With Acute Wheeze

BACKGROUND

Acute wheezing is one of the most common hospital presentations for young children. Respiratory syncytial virus (RSV) and rhinovirus (RV) species A, B and the more recently described species C are implicated in the majority of these presentations. However, the relative importance and age-specificities of these viruses have not been defined. Hence, this study aimed to establish these relationships in a large cohort of prospectively recruited hospitalized children.

METHODS

The study cohort was 390 children 0-16 years of age presenting with acute wheezing to a children's emergency department, 96.4% being admitted. A nonwheezing control population of 190 was also recruited. Nasal samples were analyzed for viruses.

RESULTS

For the first 6 months of life, RSV was the dominant virus associated with wheezing (P < 0.001). From 6 months to 2 years, RSV, RV-A and RV-C were all common but none predominated. From 2 to 6 years, RV-C was the dominant virus detected (50-60% of cases), 2-3 times more common than RV-A and RSV, RSV decreasing to be absent from 4 to 7 years. RV-B was rare at all ages. RV-C was no longer dominant in children more than 10 years of age. Overall, RV-C was associated with lower mean oxygen saturation than any other virus (P < 0.001). Controls had no clear age distribution of viruses.

CONCLUSION

This study establishes a clear profile of age specificity of virus infections causing moderate to severe wheezing in children: RSV as the dominant cause in the first 6 months and RV-C in preschool-age children.

Atopy: A Collection of Comorbid Conditions

The concept of atopy was initially developed in the first quarter of the 20th century on the basis of clinical observations without any knowledge of pathogenic mechanisms. Atopy involves a collection of comorbidities that share pathogenic features, and atopic comorbidities affect outcomes of concomitant conditions rather than existing synchronously. The clinical importance of understanding the relationship of these conditions is necessary because the treatment of one condition influences the others, and the development of one leads to or precedes the development of another. Environmental influences and multigenetic predispositions result in complex relationships among the atopic conditions sharing a type 2 pathogenesis. The specialty of Allergy and Immunology is devoted to managing the comorbidities of atopy, and better understanding of their connections can improve patient care.

Orosomucoid-like protein 3, rhinovirus and asthma

The genetic variants of orosomucoid-like protein 3 (ORMDL3) gene are associated with highly significant increases in the number of human rhinovirus (HRV)-induced wheezing episodes in children. Recent investigations have been focused on the mechanisms of ORMDL3 in rhinovirus infection for asthma and asthma exacerbations. ORMDL3 not only regulates major human rhinovirus receptor intercellular adhesion molecule 1 expression, but also plays pivotal roles in viral infection through metabolisms of ceramide and sphingosine-1-phosphate, endoplasmic reticulum (ER) stress, ER-Golgi interface and glycolysis. Research on the roles of ORMDL3 in HRV infection will lead us to identify new biomarkers and novel therapeutic targets in childhood asthma and viral induced asthma exacerbations.

Genetic diversity and epidemiology of human rhinovirus among children with severe acute respiratory tract infection in Guangzhou, China

BACKGROUND

Human rhinovirus (HRV) is one of the major viruses of acute respiratory tract disease among infants and young children. This work aimed to understand the epidemiological and phylogenetic features of HRV in Guangzhou, China. In addition, the clinical characteristics of hospitalized children infected with different subtype of HRV was investigated.

METHODS

Hospitalized children aged < 14 years old with acute respiratory tract infections were enrolled from August 2018 to December 2019. HRV was screened for by a real-time reverse-transcription PCR targeting the viral 5'UTR.

RESULTS

HRV was detected in 6.41% of the 655 specimens. HRV infection was frequently observed in children under 2 years old (57.13%). HRV-A and HRV-C were detected in 18 (45%) and 22 (55%) specimens. All 40 HRV strains detected were classified into 29 genotypes. The molecular evolutionary rate of HRV-C was estimated to be 3.34 × 10^-3 substitutions/site/year and was faster than HRV-A (7.79 × 10^-4 substitutions/site/year). Children who experienced rhinorrhoea were more common in the HRV-C infection patients than HRV-A. The viral load was higher in HRV-C detection group than HRV-A detection group (p = 0.0148). The median peak symptom score was higher in patients with HRV-C infection as compared to HRV-A (p = 0.0543), even though the difference did not significance.

CONCLUSION

This study revealed the molecular epidemiological characteristics of HRV in patients with respiratory infections in southern China. Children infected with HRV-C caused more severe disease characteristics than HRV-A, which might be connected with higher viral load in patients infected with HRV-C. These findings will provide valuable information for the pathogenic mechanism and treatment of HRV infection.

Cellular and molecular mechanisms of allergic asthma

Asthma is a chronic disease of the airways, which affects more than 350 million people worldwide. It is the most common chronic disease in children, affecting at least 30 million children and young adults in Europe. Asthma is a complex, partially heritable disease with a marked heterogeneity. Its development is influenced both by genetic and environmental factors. The most common, as well as the most well characterized subtype of asthma is allergic eosinophilic asthma, which is characterized by a type 2 airway inflammation. The prevalence of asthma has substantially increased in industrialized countries during the last 60 years. The mechanisms underpinning this phenomenon are incompletely understood, however increased exposure to various environmental pollutants probably plays a role. Disease inception is thought to be enabled by a disadvantageous shift in the balance between protective and harmful lifestyle and environmental factors, including exposure to protective commensal microbes versus infection with pathogens, collectively leading to airway epithelial cell damage and disrupted barrier integrity. Epithelial cell-derived cytokines are one of the main drivers of the type 2 immune response against innocuous allergens, ultimately leading to infiltration of lung tissue with type 2 T helper (T_H2) cells, type 2 innate lymphoid cells (ILC2s), M2 macrophages and eosinophils. This review outlines the mechanisms responsible for the orchestration of type 2 inflammation and summarizes the novel findings, including but not limited to dysregulated epithelial barrier integrity, alarmin release and innate lymphoid cell stimulation.

Pervasive positive selection on virus receptors driven by host-virus conflicts in mammals

Viruses hijack cellular proteins known as viral receptors to initiate their infection. Viral receptors are subject to two conflicting directional forces, namely negative selection to maintain their cellular function and positive selection resulted from everchanging host-virus arms race. Much remains unclear how viral receptors evolved in mammals, and whether viral receptors from different mammal groups experienced different strength of natural selection. Here, we perform evolutionary analyses of 92 viral receptors in five major orders of mammals, including Carnivora, Cetartiodactyla, Chiroptera, Primates, and Rodentia. In all the five mammal orders, signals of positive selection are detected for a high proportion of viral receptors (from 41% in Carnivora to 65% in Rodentia). Many positively selected residues overlap host-virus interaction interface. Compared with control genes, we find viral receptors underwent elevated rate of adaptive evolution in all the five mammal orders, suggesting that host-virus conflicts are the main driver of the adaptive evolution of viral receptors in mammals. Interestingly, the overall strength of natural selection acting on viral receptors driven by host-virus arms race is largely homogenous and correlated among different mammal orders with bats and rodents, zoonosis reservoirs of importance, unexceptional. Taken together, our findings indicate host-virus conflicts have driven the elevated rate of adaptive evolution in viral receptors across mammals, and might have important implications in zoonosis surveillance and prediction. Importance Viral receptors are cellular proteins hijacked by viruses to help their infections. A complete picture on the evolution of viral receptors in mammals is still lacking. Here, we perform a comprehensive evolutionary analysis of the evolution of 92 viral receptors in five mammal orders, including Carnivora, Cetartiodactyla, Chiroptera, Primates, and Rodentia. We find that positive selection pervasively occurred during the evolution of viral receptors, and viral receptors exhibit at an elevated rate of adaptive evolution than control genes in all the five mammal orders, suggesting host-virus conflicts are a major driver of the adaptive evolution of viral receptors. Interestingly, the strength of positive selection acting on viral receptors is similar among the five mammal orders. Our study might have important implications in understanding the evolution of host-virus interaction.

Prevention and Outpatient Treatment of Asthma Exacerbations in Children

Acute exacerbations cause significant morbidity and mortality in children with asthma worldwide. Although exacerbations can be minor and transient, in some children they are recurrent and significantly adversely impact quality of life. Children with frequent exacerbations account for a disproportionate amount of unscheduled care in nonprimary health facilities. Frequent exacerbators are often prescribed controller medications, but poor adherence is common. Major predictors for asthma exacerbations include genetic, social, comorbid, biological, and environmental factors. Although virus infections are a key trigger for exacerbations, other environmental factors also significantly increase risk. A previous exacerbation is a major risk factor for future exacerbations and thus identifies children to target for prevention of future episodes. In this review, we discuss both modifiable and fixed factors associated with asthma exacerbations, how to assess children for risk, and which pharmacological and nonpharmacological interventions may be of benefit. Finally, we review the current evidence around treatment within the outpatient setting for an emerging exacerbation.

Seasonal Coronaviruses and Other Neglected Respiratory Viruses: A Global Perspective and a Local Snapshot

Respiratory viral infections are the leading cause of morbidity and mortality in the world; however, there are several groups of viruses that are insufficiently routinely sought for, and can thus be considered neglected from a diagnostic and clinical standpoint. Timely detection of seasonality of certain respiratory viruses (e.g., enveloped viruses such as seasonal coronaviruses) in the local context can aid substantially in targeted and cost-effective utilization of viral diagnostic approaches. For the other, non-enveloped and year-round viruses (i.e., rhinovirus, adenovirus, and bocavirus), a continuous virological diagnosis needs to be implemented in clinical laboratories to more effectively address the aetiology of respiratory infections, and assess the overall impact of these viruses on disease burden. While the coronavirus disease 2019 (COVID-19) pandemic is still actively unfolding, we aimed to emphasize the persistent role of seasonal coronaviruses, rhinoviruses, adenoviruses and bocaviruses in the aetiology of respiratory infections. Consequently, this paper concentrates on the burden and epidemiological trends of aforementioned viral groups on a global level, but also provides a snapshot of their prevalence patterns in Croatia in order to underscore the potential implications of viral seasonality. An overall global prevalence in respiratory tract infections was found to be between 0.5 and 18.4% for seasonal coronaviruses, between 13 and 59% for rhinoviruses, between 1 and 36% for human adenoviruses, and between 1 and 56.8% for human bocaviruses. A Croatian dataset on patients with respiratory tract infection and younger than 18 years of age has revealed a fairly high prevalence of rhinoviruses (33.4%), with much lower prevalence of adenoviruses (15.6%), seasonal coronaviruses (7.1%), and bocaviruses (5.3%). These insights represent a relevant discussion point in the context of the COVID-19 pandemic where the testing of non-SARS-CoV-2 viruses has been limited in many settings, making the monitoring of disease burden associated with other respiratory viruses rather difficult.

Epithelial Barrier Dysfunction in Chronic Respiratory Diseases

Mucosal surfaces are lined by epithelial cells, which provide a complex and adaptive module that ensures first-line defense against external toxics, irritants, antigens, and pathogens. The underlying mechanisms of host protection encompass multiple physical, chemical, and immune pathways. In the lung, inhaled agents continually challenge the airway epithelial barrier, which is altered in chronic diseases such as chronic obstructive pulmonary disease, asthma, cystic fibrosis, or pulmonary fibrosis. In this review, we describe the epithelial barrier abnormalities that are observed in such disorders and summarize current knowledge on the mechanisms driving impaired barrier function, which could represent targets of future therapeutic approaches.