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

Emerging concepts and challenges in implementing the exposome paradigm in allergic diseases and asthma: a Practall document

Exposome research can improve the understanding of the mechanistic connections between exposures and health to help mitigate adverse health outcomes across the life span. The exposomic approach provides a risk profile instead of single predictors and thus is particularly applicable to allergic diseases and asthma. Under the PRACTALL collaboration between the European Academy of Allergy and Clinical Immunology (EAACI) and the American Academy of Allergy, Asthma, and Immunology (AAAAI), we evaluated the current concepts and the unmet needs on the role of the exposome in allergic diseases and asthma.

ACBD3 Is an Essential Pan-enterovirus Host Factor That Mediates the Interaction between Viral 3A Protein and Cellular Protein PI4KB

The enterovirus genus of the picornavirus family includes a large number of important human pathogens such as poliovirus, coxsackievirus, enterovirus A71, and rhinoviruses. Like all other positive-strand RNA viruses, genome replication of enteroviruses occurs on rearranged membranous structures called replication organelles (ROs). Phosphatidylinositol 4-kinase IIIβ (PI4KB) is required by all enteroviruses for RO formation. The enteroviral 3A protein recruits PI4KB to ROs, but the exact mechanism remains elusive. Here, we investigated the role of acyl-coenzyme A binding domain containing 3 (ACBD3) in PI4KB recruitment upon enterovirus replication using ACBD3 knockout (ACBD3^KO) cells. ACBD3 knockout impaired replication of representative viruses from four enterovirus species and two rhinovirus species. PI4KB recruitment was not observed in the absence of ACBD3. The lack of ACBD3 also affected the localization of individually expressed 3A, causing 3A to localize to the endoplasmic reticulum instead of the Golgi. Reconstitution of wild-type (wt) ACBD3 restored PI4KB recruitment and 3A localization, while an ACBD3 mutant that cannot bind to PI4KB restored 3A localization, but not virus replication. Consistently, reconstitution of a PI4KB mutant that cannot bind ACBD3 failed to restore virus replication in PI4KB^KO cells. Finally, by reconstituting ACBD3 mutants lacking specific domains in ACBD3^KO cells, we show that acyl-coenzyme A binding (ACB) and charged-amino-acid region (CAR) domains are dispensable for 3A-mediated PI4KB recruitment and efficient enterovirus replication. Altogether, our data provide new insight into the central role of ACBD3 in recruiting PI4KB by enterovirus 3A and reveal the minimal domains of ACBD3 involved in recruiting PI4KB and supporting enterovirus replication.IMPORTANCE Similar to all other positive-strand RNA viruses, enteroviruses reorganize host cellular membranes for efficient genome replication. A host lipid kinase, PI4KB, plays an important role in this membrane rearrangement. The exact mechanism of how enteroviruses recruit PI4KB was unclear. Here, we revealed a role of a Golgi-residing protein, ACBD3, as a mediator of PI4KB recruitment upon enterovirus replication. ACBD3 is responsible for proper localization of enteroviral 3A proteins in host cells, which is important for 3A to recruit PI4KB. By testing ACBD3 and PI4KB mutants that abrogate the ACBD3-PI4KB interaction, we showed that this interaction is crucial for enterovirus replication. The importance of specific domains of ACBD3 was evaluated for the first time, and the domains that are essential for enterovirus replication were identified. Our findings open up a possibility for targeting ACBD3 or its interaction with enteroviruses as a novel strategy for the development of broad-spectrum antienteroviral drugs.

Rhinoviruses and Their Receptors

Human rhinoviruses (RVs) are picornaviruses that can cause a variety of upper and lower respiratory tract illnesses, including the common cold, bronchitis, pneumonia, and exacerbations of chronic respiratory diseases such as asthma. There are currently > 160 known types of RVs classified into three species (A, B, and C) that use three different cellular membrane glycoproteins expressed in the respiratory epithelium to enter the host cell. These viral receptors are intercellular adhesion molecule 1 (used by the majority of RV-A and all RV-B types), low-density lipoprotein receptor family members (used by 12 RV-A types), and cadherin-related family member 3 (CDHR3; used by RV-C). RV-A and RV-B interactions with intercellular adhesion molecule 1 and low-density lipoprotein receptor glycoproteins are well defined and their cellular functions have been described, whereas the mechanisms of the RV-C interaction with CDHR3 and its cellular functions are being studied. A single nucleotide polymorphism (rs6967330) in CDHR3 increases cell surface expression of this protein and, as a result, also promotes RV-C infections and illnesses. There are currently no approved vaccines or antiviral therapies available to treat or prevent RV infections, which is a major unmet medical need. Understanding interactions between RV and cellular receptors could lead to new insights into the pathogenesis of respiratory illnesses as well as lead to new approaches to control respiratory illnesses caused by RV infections.

DUSP10 Negatively Regulates the Inflammatory Response to Rhinovirus through Interleukin-1β Signaling

Rhinoviruses are one of the causes of the common cold. In patients with asthma or chronic obstructive pulmonary disease, viral infections, including those with rhinovirus, are the commonest cause of exacerbations. Novel therapeutics to limit viral inflammation are clearly required. The work presented here identifies DUSP10 as an important protein involved in limiting the inflammatory response in the airway without affecting immune control of the virus.

Rhinoviral infection is a common trigger of the excessive inflammation observed during exacerbations of asthma and chronic obstructive pulmonary disease. Rhinovirus (RV) recognition by pattern recognition receptors activates the mitogen-activated protein kinase (MAPK) pathways, which are common inducers of inflammatory gene production. A family of dual-specificity phosphatases (DUSPs) can regulate MAPK function, but their roles in rhinoviral infection are not known. We hypothesized that DUSPs would negatively regulate the inflammatory response to RV infection. Our results revealed that the p38 and c-Jun N-terminal kinase (JNK) MAPKs play key roles in the inflammatory response of epithelial cells to RV infection. Three DUSPs previously shown to have roles in innate immunity (DUSPs 1, 4, and 10) were expressed in primary bronchial epithelial cells, and one of them, DUSP10, was downregulated by RV infection. Small interfering RNA-mediated knockdown of DUSP10 identified a role for the protein in negatively regulating inflammatory cytokine production in response to interleukin-1β (IL-1β), alone and in combination with RV, without any effect on RV replication. This study identifies DUSP10 as an important regulator of airway inflammation in respiratory viral infection.

IMPORTANCE Rhinoviruses are one of the causes of the common cold. In patients with asthma or chronic obstructive pulmonary disease, viral infections, including those with rhinovirus, are the commonest cause of exacerbations. Novel therapeutics to limit viral inflammation are clearly required. The work presented here identifies DUSP10 as an important protein involved in limiting the inflammatory response in the airway without affecting immune control of the virus.

Lethal Respiratory Disease Associated with Human Rhinovirus C in Wild Chimpanzees, Uganda, 2013

We describe a lethal respiratory outbreak among wild chimpanzees in Uganda in 2013 for which molecular and epidemiologic analyses implicate human rhinovirus C as the cause. Postmortem samples from an infant chimpanzee yielded near-complete genome sequences throughout the respiratory tract; other pathogens were absent. Epidemiologic modeling estimated the basic reproductive number (R₀) for the epidemic as 1.83, consistent with the common cold in humans. Genotyping of 41 chimpanzees and examination of 24 published chimpanzee genomes from subspecies across Africa showed universal homozygosity for the cadherin-related family member 3 CDHR3-Y₅₂₉ allele, which increases risk for rhinovirus C infection and asthma in human children. These results indicate that chimpanzees exhibit a species-wide genetic susceptibility to rhinovirus C and that this virus, heretofore considered a uniquely human pathogen, can cross primate species barriers and threatens wild apes. We advocate engineering interventions and prevention strategies for rhinovirus infections for both humans and wild apes.

Lessons Learned From GWAS of Asthma

Asthma is a common complex disease of the airways. Genome-wide association studies (GWASs) of asthma have identified many risk alleles and loci that have been replicated in worldwide populations. Although the risk alleles identified by GWAS have small effects and explain only a small portion of prevalence, the discovery of asthma loci can provide an understanding of its genetic architecture and the molecular pathways involved in disease pathogenesis. These discoveries can translate into advances in clinical care by identifying therapeutic targets, preventive strategies and ultimately approaches for personalized medicine. In this review, we summarize results from GWAS of asthma from the past 10 years and the insights gleaned from these discoveries.

Bronchiolitis needs a revisit: Distinguishing between virus entities and their treatments

Current data indicate that the “bronchiolitis” diagnosis comprises more than one condition. Clinically, pathophysiologically, and even genetically three main clusters of patients can be identified among children suffering from severe bronchiolitis (or first wheezing episode): (a) respiratory syncytial virus (RSV)‐induced bronchiolitis, characterized by young age of the patient, mechanical obstruction of the airways due to mucus and cell debris, and increased risk of recurrent wheezing. For this illness, an effective prophylactic RSV‐specific monoclonal antibody is available; (b) rhinovirus‐induced wheezing, associated with atopic predisposition of the patient and high risk of subsequent asthma development, which may, however, be reversed with systemic corticosteroids in those with severe illness; and (c) wheeze due to other viruses, characteristically likely to be less frequent and severe. Clinically, it is important to distinguish between these partially overlapping patient groups as they are likely to respond to different treatments. It appears that the first episode of severe bronchiolitis in under 2‐year‐old children is a critical event and an important opportunity for designing secondary prevention strategies for asthma. As data have shown bronchiolitis cannot simply be diagnosed using a certain cutoff age, but instead, as we suggest, using the viral etiology as the differentiating factor.

Exacerbations of chronic respiratory diseases

Respiratory viral infections including human rhinovirus (RV) infection have been identified as the most important environmental trigger of exacerbations of chronic lung diseases. While well established as the most common viral infections associated with exacerbations of asthma and chronic obstructive pulmonary disease, RVs and other respiratory viruses are also now thought to be important in triggering exacerbations of cystic fibrosis and the interstitial lung diseases. Here, we summarize the epidemiological evidence the supports respiratory viruses including RV as triggers of exacerbations of chronic lung diseases. We propose that certain characteristics of RVs may explain why they are the most common trigger of exacerbations of chronic lung diseases. We further highlight the latest mechanistic evidence supporting how and why common respiratory viral infections may enhance and promote disease triggering exacerbation events, through their interactions with the host immune system, and may be affected by ongoing treatments. We also provide a commentary on how new treatments may better manage the disease burden associated with respiratory viral infections and the exacerbation events that they trigger.

Pathophysiological Mechanisms of Asthma

The recent Lancet commission has highlighted that "asthma" should be used to describe a clinical syndrome of wheeze, breathlessness, chest tightness, and sometimes cough. The next step is to deconstruct the airway into components of fixed and variable airflow obstruction, inflammation, infection and altered cough reflex, setting the airway disease in the context of extra-pulmonary co-morbidities and social and environmental factors. The emphasis is always on delineating treatable traits, including variable airflow obstruction caused by airway smooth muscle constriction (treated with short- and long-acting β-2 agonists), eosinophilic airway inflammation (treated with inhaled corticosteroids) and chronic bacterial infection (treated with antibiotics with benefit if it is driving the disease). It is also important not to over-treat the untreatable, such as fixed airflow obstruction. These can all be determined using simple, non-invasive tests such as spirometry before and after acute administration of a bronchodilator (reversible airflow obstruction); peripheral blood eosinophil count, induced sputum, exhaled nitric oxide (airway eosinophilia); and sputum or cough swab culture (bacterial infection). Additionally, the pathophysiology of risk domains must be considered: these are risk of an asthma attack, risk of poor airway growth, and in pre-school children, risk of progression to eosinophilic school age asthma. Phenotyping the airway will allow more precise diagnosis and targeted treatment, but it is important to move to endotypes, especially in the era of increasing numbers of biologicals. Advances in -omics technology allow delineation of pathways, which will be particularly important in TH2 low eosinophilic asthma, and also pauci-inflammatory disease. It is very important to appreciate the difficulties of cluster analysis; a patient may have eosinophilic airway disease because of a steroid resistant endotype, because of non-adherence to basic treatment, and a surge in environmental allergen burden. Sophisticated -omics approaches will be reviewed in this manuscript, but currently they are not being used in clinical practice. However, even while they are being evaluated, management of the asthmas can and should be improved by considering the pathophysiologies of the different airway diseases lumped under that umbrella term, using simple, non-invasive tests which are readily available, and treating accordingly.

DNA methylation in nasal epithelium, atopy, and atopic asthma in children: a genome-wide study

BACKGROUND

Epigenetic mechanisms could alter the airway epithelial barrier and ultimately lead to atopic diseases such as asthma. We aimed to identify DNA methylation profiles that are associated with-and could accurately classify-atopy and atopic asthma in school-aged children.

METHODS

We did a genome-wide study of DNA methylation in nasal epithelium and atopy or atopic asthma in 483 Puerto Rican children aged 9-20 years, recruited using multistage probability sampling. Atopy was defined as at least one positive IgE (≥0·35 IU/mL) to common aeroallergens, and asthma was defined as a physician's diagnosis plus wheeze in the previous year. Significant (false discovery rate p<0·01) methylation signals were correlated with gene expression, and top CpGs were validated by pyrosequencing. We then replicated our top methylation findings in a cohort of 72 predominantly African American children, and in 432 children from a European birth cohort. Next, we tested classification models based on nasal methylation for atopy or atopic asthma in all cohorts.

FINDINGS

DNA methylation profiles were markedly different between children with (n=312) and without (n=171) atopy in the Puerto Rico discovery cohort, recruited from Feb 12, 2014, until May 8, 2017. After adjustment for covariates and multiple testing, we found 8664 differentially methylated CpGs by atopy, with false discovery rate-adjusted p values ranging from 9·58 × 10^-17 to 2·18 × 10^-22 for the top 30 CpGs. These CpGs were in or near genes relevant to epithelial barrier function, including CDHR3 and CDH26, and in other genes related to airway epithelial integrity and immune regulation, such as FBXL7, NTRK1, and SLC9A3. Moreover, 28 of the top 30 CpGs replicated in the same direction in both independent cohorts. Classification models of atopy based on nasal methylation performed well in the Puerto Rico cohort (area under the curve [AUC] 0·93-0·94 and accuracy 85-88%) and in both replication cohorts (AUC 0·74-0·92, accuracy 68-82%). The models also performed well for atopic asthma in the Puerto Rico cohort (AUC 0·95-1·00, accuracy 88%) and the replication cohorts (AUC 0·82-0·88, accuracy 86%).

INTERPRETATION

We identified specific methylation profiles in airway epithelium that are associated with atopy and atopic asthma in children, and a nasal methylation panel that could classify children by atopy or atopic asthma. Our findings support the feasibility of using the nasal methylome for future clinical applications, such as predicting the development of asthma among wheezing infants.

FUNDING

US National Institutes of Health.

Small Animal Models of Respiratory Viral Infection Related to Asthma

Respiratory viral infections are strongly associated with asthma exacerbations. Rhinovirus is most frequently-detected pathogen; followed by respiratory syncytial virus; metapneumovirus; parainfluenza virus; enterovirus and coronavirus. In addition; viral infection; in combination with genetics; allergen exposure; microbiome and other pathogens; may play a role in asthma development. In particular; asthma development has been linked to wheezing-associated respiratory viral infections in early life. To understand underlying mechanisms of viral-induced airways disease; investigators have studied respiratory viral infections in small animals. This report reviews animal models of human respiratory viral infection employing mice; rats; guinea pigs; hamsters and ferrets. Investigators have modeled asthma exacerbations by infecting mice with allergic airways disease. Asthma development has been modeled by administration of virus to immature animals. Small animal models of respiratory viral infection will identify cell and molecular targets for the treatment of asthma.

CDHR3 extracellular domains EC1-3 mediate rhinovirus C interaction with cells and as recombinant derivatives, are inhibitory to virus infection

Viruses in the rhinovirus C species (RV-C) are more likely to cause severe wheezing illnesses and asthma exacerbations in children than related isolates of the RV-A or RV-B. The RV-C capsid is structurally distinct from other rhinoviruses and does not bind ICAM-1 or LDL receptors. The RV-C receptor is instead, human cadherin-related family member 3 (CDHR3), a protein unique to the airway epithelium. A single nucleotide polymorphism (rs6967330, encoding C529Y) in CDHR3 regulates the display density of CDHR3 on cell surfaces and is among the strongest known genetic correlates for childhood virus-induced asthma susceptibility. CDHR3 immunoprecipitations from transfected or transduced cell lysates were used to characterize the RV-C interaction requirements. The C529 and Y529 variations in extracellular repeat domain 5 (EC5), bound equivalently to virus. Glycosylase treatment followed by mass spectrometry mapped 3 extracellular N-linked modification sites, and further detected surface-dependent, α2-6 sialyation unique to the Y529 format. None of these modifications were required for RV-C recognition, but removal or even dilution of structurally stabilizing calcium ions from the EC junctions irreversibly abrogated virus binding. CDHR3 deletions expressed in HeLa cells or as bacterial recombinant proteins, mapped the amino-terminal EC1 unit as the required virus contact. Derivatives containing the EC1 domain, could not only recapitulate virus:receptor interactions in vitro, but also directly inhibit RV-C infection of susceptible cells for several virus genotypes (C02, C15, C41, and C45). We propose that all RV-C use the same EC1 landing pad, interacting with putative EC3-mediated multimerization formats of CDHR3.

A Single Point Mutation in the Rhinovirus 2B Protein Reduces the Requirement for Phosphatidylinositol 4-Kinase Class III Beta in Viral Replication

Rhinoviruses (RVs) replicate on cytoplasmic membranes derived from the Golgi apparatus. They encode membrane-targeted proteins 2B, 2C, and 3A, which control trafficking and lipid composition of the replication membrane. The virus recruits host factors for replication, such as phosphatidylinositol 4 (PI4)-kinase 3beta (PI4K3b), which boosts PI4-phosphate (PI4P) levels and drives lipid countercurrent exchange of PI4P against cholesterol at endoplasmic reticulum-Golgi membrane contact sites through the lipid shuttling protein oxysterol binding protein 1 (OSBP1). We identified a PI4K3b inhibitor-resistant RV-A16 variant with a single point mutation in the conserved 2B protein near the cytosolic carboxy terminus, isoleucine 92 to threonine (termed 2B[I92T]). The mutation did not confer resistance to cholesterol-sequestering compounds or OSBP1 inhibition, suggesting invariant dependency on the PI4P/cholesterol lipid countercurrents. In the presence of PI4K3b inhibitor, Golgi reorganization and PI4P lipid induction occurred in RV-A16 2B[I92] but not in wild-type infection. The knockout of PI4K3b abolished the replication of both the 2B[I92T] mutant and the wild type. Doxycycline-inducible expression of PI4K3b in PI4K3b knockout cells efficiently rescued the 2B[I92T] mutant and, less effectively, wild-type virus infection. Ectopic expression of 2B[I92T] or 2B was less efficient than that of 3A in recruiting PI4K3b to perinuclear membranes, suggesting a supportive rather than decisive role of 2B in recruiting PI4K3b. The data suggest that 2B tunes the recruitment of PI4K3b to the replication membrane and allows the virus to adapt to cells with low levels of PI4K3b while still maintaining the PI4P/cholesterol countercurrent for establishing Golgi-derived RV replication membranes.IMPORTANCE Human rhinoviruses (RVs) are the major cause of the common cold worldwide. They cause asthmatic exacerbations and chronic obstructive pulmonary disease. Despite recent advances, the development of antivirals and vaccines has proven difficult due to the high number and variability of RV types. The identification of critical host factors and their interactions with viral proteins and membrane lipids for the establishment of viral replication is a basis for drug development strategies. Our findings here shed new light on the interactions between nonstructural viral membrane proteins and class III phosphatidylinositol 4 kinases from the host and highlight the importance of phosphatidylinositol 4 phosphate for RV replication.

Elucidating the Interaction of CF Airway Epithelial Cells and Rhinovirus: Using the Host-Pathogen Relationship to Identify Future Therapeutic Strategies

Chronic lung disease remains the primary cause of mortality in cystic fibrosis (CF). Growing evidence suggests respiratory viral infections are often more severe in CF compared to healthy peers and contributes to pulmonary exacerbations (PEx) and deterioration of lung function. Rhinovirus is the most prevalent respiratory virus detected, particularly during exacerbations in children with CF <5 years old. However, even though rhinoviral infections are likely to be one of the factors initiating the onset of CF lung disease, there is no effective targeted treatment. A better understanding of the innate immune responses by CF airway epithelial cells, the primary site of infection for viruses, is needed to identify why viral infections are more severe in CF. The aim of this review is to present the clinical impact of virus infection in both young children and adults with CF, focusing on rhinovirus infection. Previous in vitro and in vivo investigations looking at the mechanisms behind virus infection will also be summarized. The review will finish on the potential of transcriptomics to elucidate the host-pathogen responses by CF airway cells to viral infection and identify novel therapeutic targets.

Modulation of airway hyperresponsiveness by rhinovirus exposure

Rhinovirus (RV) exposure has been implicated in childhood development of wheeze evoking asthma and exacerbations of underlying airways disease. Studies such as the Copenhagen Prospective Studies on Asthma in Childhood (COPSAC) and Childhood Origins of ASThma (COAST) have identified RV as a pathogen inducing severe respiratory disease. RVs also modulate airway hyperresponsiveness (AHR), a key characteristic of such diseases. Although potential factors underlying mechanisms by which RV induces AHR have been postulated, the precise mechanisms of AHR following RV exposure remain elusive.

A challenge to RV-related research stems from inadequate models for study. While human models raise ethical concerns and are relatively difficult in terms of subject recruitment, murine models are limited by susceptibility of infection to the relatively uncommon minor group (RV-B) serotypes, strains that are generally associated with infrequent clinical respiratory virus infections. Although a transgenic mouse strain that has been developed has enhanced susceptibility for infection with the common major group (RV-A) serotypes, few studies have focused on RV in the context of allergic airways disease rather than understanding RV-induced AHR. Recently, the receptor for the virulent RV-C CDHR3, was identified, but a dearth of studies have examined RV-C-induced effects in humans.

Currently, the mechanisms by which RV infections modulate airway smooth muscle (ASM) shortening or excitation-contraction coupling remain elusive. Further, only one study has investigated the effects of RV on bronchodilatory mechanisms, with only speculation as to mechanisms underlying RV-mediated modulation of bronchoconstriction.

Non-atopic rhinitis at age 6 is associated with subsequent development of asthma

BACKGROUND

It has been postulated that the association between allergic rhinitis and asthma is attributable to the progressive clinical expression of respiratory inflammation during childhood. The role of non-allergic rhinitis in early life in relation to subsequent asthma has not been extensively explored.

OBJECTIVE

We sought to determine whether rhinitis in early life was associated with risk of asthma development into adulthood, and whether this relationship is independent of allergic sensitization.

METHODS

Participants were identified from the Tucson Children's Respiratory Study, a non-selected birth cohort. Allergy skin prick testing was performed at age 6 years using house dust mix, Bermuda, mesquite, olive, mulberry, careless weed, and Alternaria aeroallergens. Atopy was defined as ≥1 positive tests. Physician-diagnosed active asthma from age 6 to 32 and physician-diagnosed rhinitis at age 6 were determined by questionnaire. Participants with asthma or active wheezing at age 6 were excluded from analyses. Risk estimates were obtained with Cox regression.

RESULTS

There were 521 participants who met inclusion criteria. The hazard ratio for subsequently acquiring a diagnosis of asthma between the ages of 8 and 32 for those with non-atopic rhinitis was 2.1 (95% CI: 1.2, 3.4, P = 0.005), compared with the non-atopic no rhinitis group, after adjusting for sex, ethnicity, maternal asthma, maternal education and smoking, and history of 4+ colds per year at age 6. Among the atopic participants, both the active and no rhinitis groups were more likely to develop and have asthma through age 32. The relation between non-atopic rhinitis and asthma was independent of total serum IgE levels at age 6.

CONCLUSION AND CLINICAL RELEVANCE

Childhood rhinitis, even in the absence of atopy, confers significant risk for asthma development through adulthood. These findings underscore the importance of non-allergic mechanisms in the development of asthma.

HaCaT epithelial cells as an innovative novel model of rhinovirus infection and impact of clarithromycin treatment on infection kinetics

The in vitro propagation of human rhinoviruses (RVs) is difficult because only few continuous human cell lines are permissive to these agents. We propose an innovative model of epithelial cell infection using a non-transformed continuous keratinocyte line from human origin (HaCaT cells). After infection with RV-A13, RV-A16 or RV-A19, HaCaT cells produced infectious particles without showing any observable cytopathic effect and overexpressed ICAM-1 (intercellular adhesion molecule 1), the major entry receptor of RVs. Furthermore, the treatment of HaCaT cells with 10 µM clarithromycin reduced the viral titer by 93% and 60% during the first and second days following viral infection, respectively, probably by down-regulating ICAM-1 expression. This original model of epithelial cell infection by RV could be useful to study chronic viral infection and bacterium-virus interactions at the cell level. These results also suggest that clarithromycin may be evaluated for treating in vivo infections associating RV to a susceptible bacterium.

Involvement and Possible Role of Eosinophils in Asthma Exacerbation

Eosinophils are involved in the development of asthma exacerbation. Recent studies have suggested that sputum and blood eosinophil counts are important factors for predicting asthma exacerbation. In severe eosinophilic asthma, anti-interleukin (IL)-5 monoclonal antibody decreases blood eosinophil count and asthma exacerbation frequency. However, even in the absence of IL-5, eosinophilic airway inflammation can be sufficiently maintained by the T helper (Th) 2 network, which comprises a cascade of vascular cell adhesion molecule-1/CC chemokines/eosinophil growth factors, including granulocyte-macrophage colony-stimulating factor (GM-CSF). Periostin, an extracellular matrix protein and a biomarker of the Th2 immune response in asthma, directly activates eosinophils in vitro. A major cause of asthma exacerbation is viral infection, especially rhinovirus (RV) infection. The expression of intercellular adhesion molecule (ICAM)-1, a cellular receptor for the majority of RVs, on epithelial cells is increased after RV infection, and adhesion of eosinophils to ICAM-1 can upregulate the functions of eosinophils. The expressions of cysteinyl leukotrienes (cysLTs) and CXCL10 are upregulated in virus-induced asthma. CysLTs can directly provoke eosinophilic infiltration in vivo and activate eosinophils in vitro. Furthermore, eosinophils express the CXC chemokine receptor 3, and CXCL10 activates eosinophils in vitro. Both eosinophils and neutrophils contribute to the development of severe asthma or asthma exacerbation. IL-8, which is an important chemoattractant for neutrophils, is upregulated in some cases of severe asthma. Lipopolysaccharide (LPS), which induces IL-8 from epithelial cells, is also increased in the lower airways of corticosteroid-resistant asthma. IL-8 or LPS-stimulated neutrophils increase the transbasement membrane migration of eosinophils, even in the absence of chemoattractants for eosinophils. Therefore, eosinophils are likely to contribute to the development of asthma exacerbation through several mechanisms, including activation by Th2 cytokines, such as IL-5 or GM-CSF or by virus infection-related proteins, such as CXCL10, and interaction with other cells, such as neutrophils.

Recent advances in understanding rhinovirus immunity

Rhinoviruses are the most common cause of upper respiratory tract infections. However, they can induce exacerbations of chronic obstructive pulmonary disease and asthma, bronchiolitis in infants, and significant lower respiratory tract infections in children, the immunosuppressed, and the elderly. The large number of rhinovirus strains (currently about 160) and their antigenic diversity are significant obstacles in vaccine development. The phenotype of immune responses induced during rhinovirus infection can affect disease severity. Recognition of rhinovirus and a balance of innate responses are important factors in rhinovirus-induced morbidity. Immune responses to rhinovirus infections in healthy individuals are typically of the T helper type 1 (Th1) phenotype. However, rhinovirus-driven asthma exacerbations are additionally characterised by an amplified Th2 immune response and airway neutrophilia. This commentary focuses on recent advances in understanding immunity toward rhinovirus infection and how innate and adaptive immune responses drive rhinovirus-induced asthma exacerbations.

Structure-Based Drug Design of Potent Pyrazole Derivatives against Rhinovirus Replication

Rhinoviruses (RVs) have been linked to exacerbations of many pulmonary diseases, thus increasing morbidity and/or mortality in subjects at risk. Unfortunately, the wide variety of RV genotypes constitutes a major hindrance for the development of Rhinovirus replication inhibitors. In the current investigation, we have developed a novel series of pyrazole derivatives that potently inhibit the Rhinovirus replication. Compounds 10e and 10h behave as early stage inhibitors of Rhinovirus infection with a broad-spectrum activity against RV-A and RV-B species (EC₅₀ < 0.1 μM). We also evaluate the dynamics of the emerging resistance of these promising compounds and their in vitro genotoxicity. Molecular docking experiments shed light on the pharmacophoric elements interacting with residues of the drug-binding pocket.

Gene editing in the context of an increasingly complex genome

The reporting of the first draft of the human genome in 2000 brought with it much hope for the future in what was felt as a paradigm shift toward improved health outcomes. Indeed, we have now mapped the majority of variation across human populations with landmark projects such as 1000 Genomes; in cancer, we have catalogued mutations across the primary carcinomas; whilst, for other diseases, we have identified the genetic variants with strongest association. Despite this, we are still awaiting the genetic revolution in healthcare to materialise and translate itself into the health benefits for which we had hoped. A major problem we face relates to our underestimation of the complexity of the genome, and that of biological mechanisms, generally. Fixation on DNA sequence alone and a 'rigid' mode of thinking about the genome has meant that the folding and structure of the DNA molecule -and how these relate to regulation- have been underappreciated. Projects like ENCODE have additionally taught us that regulation at the level of RNA is just as important as that at the spatiotemporal level of chromatin.In this review, we chart the course of the major advances in the biomedical sciences in the era pre- and post the release of the first draft sequence of the human genome, taking a focus on technology and how its development has influenced these. We additionally focus on gene editing via CRISPR/Cas9 as a key technique, in particular its use in the context of complex biological mechanisms. Our aim is to shift the mode of thinking about the genome to that which encompasses a greater appreciation of the folding of the DNA molecule, DNA- RNA/protein interactions, and how these regulate expression and elaborate disease mechanisms.Through the composition of our work, we recognise that technological improvement is conducive to a greater understanding of biological processes and life within the cell. We believe we now have the technology at our disposal that permits a better understanding of disease mechanisms, achievable through integrative data analyses. Finally, only with greater understanding of disease mechanisms can techniques such as gene editing be faithfully conducted.

Atopic asthma after rhinovirus-induced wheezing is associated with DNA methylation change in the SMAD3 gene promoter

Children with rhinovirus‐induced severe early wheezing have an increased risk of developing asthma later in life. The exact molecular mechanisms for this association are still mostly unknown. To identify potential changes in the transcriptional and epigenetic regulation in rhinovirus‐associated atopic or nonatopic asthma, we analyzed a cohort of 5‐year‐old children (n = 45) according to the virus etiology of the first severe wheezing episode at the mean age of 13 months and to 5‐year asthma outcome. The development of atopic asthma in children with early rhinovirus‐induced wheezing was associated with DNA methylation changes at several genomic sites in chromosomal regions previously linked to asthma. The strongest changes in atopic asthma were detected in the promoter region of SMAD3 gene at chr 15q22.33 and introns of DDO/METTL24 genes at 6q21. These changes were validated to be present also at the average age of 8 years.

A revised airway epithelial hierarchy includes CFTR-expressing ionocytes

The airways of the lung are the primary sites of disease in asthma and cystic fibrosis. Here we study the cellular composition and hierarchy of the mouse tracheal epithelium by single-cell RNA-sequencing (scRNA-seq) and in vivo lineage tracing. We identify a rare cell type, the Foxi1+ pulmonary ionocyte; functional variations in club cells based on their location; a distinct cell type in high turnover squamous epithelial structures that we term 'hillocks'; and disease-relevant subsets of tuft and goblet cells. We developed 'pulse-seq', combining scRNA-seq and lineage tracing, to show that tuft, neuroendocrine and ionocyte cells are continually and directly replenished by basal progenitor cells. Ionocytes are the major source of transcripts of the cystic fibrosis transmembrane conductance regulator in both mouse (Cftr) and human (CFTR). Knockout of Foxi1 in mouse ionocytes causes loss of Cftr expression and disrupts airway fluid and mucus physiology, phenotypes that are characteristic of cystic fibrosis. By associating cell-type-specific expression programs with key disease genes, we establish a new cellular narrative for airways disease.

Cellular N-myristoyltransferases play a crucial picornavirus genus-specific role in viral assembly, virion maturation, and infectivity

In nearly all picornaviruses the precursor of the smallest capsid protein VP4 undergoes co-translational N-terminal myristoylation by host cell N-myristoyltransferases (NMTs). Curtailing this modification by mutation of the myristoylation signal in poliovirus has been shown to result in severe assembly defects and very little, if any, progeny virus production. Avoiding possible pleiotropic effects of such mutations, we here used pharmacological abrogation of myristoylation with the NMT inhibitor DDD85646, a pyrazole sulfonamide originally developed against trypanosomal NMT. Infection of HeLa cells with coxsackievirus B3 in the presence of this drug decreased VP0 acylation at least 100-fold, resulting in a defect both early and late in virus morphogenesis, which diminishes the yield of viral progeny by about 90%. Virus particles still produced consisted mainly of provirions containing RNA and uncleaved VP0 and, to a substantially lesser extent, of mature virions with cleaved VP0. This indicates an important role of myristoylation in the viral maturation cleavage. By electron microscopy, these RNA-filled particles were indistinguishable from virus produced under control conditions. Nevertheless, their specific infectivity decreased by about five hundred fold. Since host cell-attachment was not markedly impaired, their defect must lie in the inability to transfer their genomic RNA into the cytosol, likely at the level of endosomal pore formation. Strikingly, neither parechoviruses nor kobuviruses are affected by DDD85646, which appears to correlate with their native capsid containing only unprocessed VP0. Individual knockout of the genes encoding the two human NMT isozymes in haploid HAP1 cells further demonstrated the pivotal role for HsNMT1, with little contribution by HsNMT2, in the virus replication cycle. Our results also indicate that inhibition of NMT can possibly be exploited for controlling the infection by a wide spectrum of picornaviruses.

PreDicta chip-based high resolution diagnosis of rhinovirus-induced wheeze

Rhinovirus (RV) infections are major triggers of acute exacerbations of severe respiratory diseases such as pre-school wheeze, asthma and chronic obstructive pulmonary disease (COPD). The occurrence of numerous RV types is a major challenge for the identification of the culprit virus types and for the improvement of virus type-specific treatment strategies. Here, we develop a chip containing 130 different micro-arrayed RV proteins and peptides and demonstrate in a cohort of 120 pre-school children, most of whom had been hospitalized due to acute wheeze, that it is possible to determine the culprit RV species with a minute blood sample by serology. Importantly, we identify RV-A and RV-C species as giving rise to most severe respiratory symptoms. Thus, we have generated a chip for the serological identification of RV-induced respiratory illness which should be useful for the rational development of preventive and therapeutic strategies targeting the most important RV types.

Antiviral therapeutic approaches for human rhinovirus infections

Human rhinoviruses are the primary etiological agent of the common cold. This infection can be mild and self-limiting in immunocompetent hosts, but can be associated with bronchiolitis in infants, pneumonia in the immunosuppressed and exacerbations of pre-existing pulmonary conditions such as asthma or chronic obstructive pulmonary disease. Many of these conditions can place significant economic costs upon healthcare infrastructure. There is currently no licensed vaccine for rhinovirus, as the large variety of rhinovirus serotypes has posed significant challenges for research. In this review, we discuss current knowledge around antiviral drugs and small molecule inhibitors of rhinovirus infection, as well as antiviral host defense peptides as exciting prospects to approach the development of novel therapeutics which target human rhinovirus.

Structural view of the 2A protease from human rhinovirus C15

The majority of outbreaks of the common cold are caused by rhinoviruses. The 2A protease (2Apro) of human rhinoviruses (HRVs) is known to play important roles in the propagation of the virus and the modulation of host signal pathways to facilitate viral replication. The 2Apro from human rhinovirus C15 (HRV-C15) has been expressed in Escherichia coli and purified by affinity chromatography, ion-exchange chromatography and gel-filtration chromatography. The crystals diffracted to 2.6 Å resolution. The structure was solved by molecular replacement using the structure of 2Apro from coxsackievirus A16 (CVA16) as the search model. The structure contains a conserved His-Asp-Cys catalytic triad and a Zn2+-binding site. Comparison with other 2Apro structures from enteroviruses reveals that the substrate-binding cleft of 2Apro from HRV-C15 exhibits a more open conformation, which presumably favours substrate binding.

Development of allergic immunity in early life

The growth and maturity of the peripheral immune system and subsequent development of pulmonary immunity in early life is dictated by host, environmental and microbial factors. Dysregulation during the critical window of immune development in the postnatal years results in disease which impacts on lifelong lung health. Asthma is a common disease in childhood and is often preceded by wheezing illnesses during the preschool years. However, the mechanisms underlying development of wheeze and how and why only some children progress to asthma is unknown. Human studies to date have generally focused on peripheral immune development, with little assessment of local tissue pathology in young children. Moreover, mechanisms underlying the interactions between inflammation and tissue repair at mucosal surfaces in early life remain unknown. Disappointingly, mechanistic studies in mice have predominantly used adult models. This review will consider the aspects of the neonatal immune system which might contribute to the development of early life wheezing disorders and asthma, and discuss the external environmental factors which may influence this process.

Reduced CDHR3 expression in children wheezing with rhinovirus

BACKGROUND

Rhinovirus-induced wheezing in young children has been associated with increased asthma risk at school age. Recently, the transmembrane protein cadherin-related family member 3 (CDHR3) was identified as the RV-C receptor and the genetic variant rs6967330 (p.Cys529Tyr) was reported to be associated with enhanced RV-C binding and increased replication in vitro. The aim of this study was to examine rs6967330 genotypes and mRNA expression of CDHR3 in relation to presence of rhinovirus and clinical symptoms in children with acute wheezing and compare to a group of age-matched healthy children.

METHODS

rs6967330;G>A was genotyped (n = 216), and CDHR3 mRNA expression was measured in peripheral blood leukocytes (n = 69) from a subgroup of children wheezing with RV infection acute and at a follow-up visit 2-3 months later, and in healthy controls. Standardized TaqMan assays were used.

RESULTS

The risk allele rs6967330-A was over-represented in the wheezing group (P < .001). Reduced mRNA levels of CDHR3 were found in children with acute wheezing as compared to the control group (P = .001). Children with the rs6967330 genotypes AA/AG showed the largest differences in CDHR3 expression between acute and follow-up visit (P < .04).

CONCLUSIONS

Preschool children with RV-induced wheezing were shown to have reduced CDHR3 mRNA levels, which might result in an increased permeability of the epithelial layers of the airways and thereby an increased vulnerability. Thus, measuring CDHR3 mRNA levels might help to identify a more severe phenotype of wheezing preschool children.

Early life risk factors for chronic sinusitis: A longitudinal birth cohort study

BACKGROUND

Chronic sinusitis is a commonly diagnosed condition in adults who frequently present with late-stage disease and irreversible changes to the sinus mucosa. Understanding the natural history of chronic sinusitis is critical in developing therapies designed to prevent or slow the progression of disease.

OBJECTIVE

We sought to determine early life risk factors for adult sinusitis in a longitudinal cohort study (Tucson Children's Respiratory Study).

METHODS

Physician-diagnosed sinusitis was reported at age 6. Adult sinusitis between 22 and 32 years was defined as self-reported sinusitis plus physician-ordered sinus radiologic films. Atopy was assessed by skin prick test. Individuals were grouped into 4 phenotypes: no sinusitis (n = 621), transient childhood sinusitis only (n = 57), late-onset adult sinusitis only (n = 68), and early onset chronic sinusitis (childhood and adult sinusitis, n = 26).

RESULTS

Sinusitis was present in 10.8% of children and 12.2% of adults. Childhood sinusitis was the strongest independent risk factor for adult sinusitis (odds ratio = 4.2; 95% CI: 2.5-7.1; P < .0001; n = 772). Early onset chronic sinusitis was associated with increased serum IgE levels as early as at 9 months of age, atopy (assessed by skin prick test reactivity), childhood eczema and allergic rhinitis, frequent childhood colds, maternal asthma, and with increased prevalence of concurrent asthma. No association was found between late-onset adult sinusitis and any of the early life risk factors studied.

CONCLUSIONS

We identified an early onset chronic sinusitis phenotype associated with a predisposition to viral infections/colds in early life, allergies, and asthma. Elucidation of the molecular mechanisms for this phenotype may lead to future therapies to prevent the progression of the disease into adult sinusitis.

Respiratory Viruses and Asthma

Asthma remains the most prevalent chronic respiratory disorder, affecting people of all ages. The relationship between respiratory virus infection and asthma has long been recognized, though remains incompletely understood. In this article, we will address key issues around this relationship. These will include the crucial role virus infection plays in early life, as a potential risk factor for the development of asthma and lung disease. We will assess the impact that virus infection has on those with established asthma as a trigger for acute disease and how this may influence asthma throughout life. Finally, we will explore the complex interaction that occurs between the airway and the immune responses that make those with asthma so susceptible to the effects of virus infection.

Three-dimensional Culture of Human Airway Epithelium in Matrigel for Evaluation of Human Rhinovirus C and Bocavirus Infections

OBJECTIVE

Newly identified human rhinovirus C (HRV-C) and human bocavirus (HBoV) cannot propagate in vitro in traditional cell culture models; thus obtaining knowledge about these viruses and developing related vaccines are difficult. Therefore, it is necessary to develop a novel platform for the propagation of these types of viruses.

METHODS

A platform for culturing human airway epithelia in a three-dimensional (3D) pattern using Matrigel as scaffold was developed. The features of 3D culture were identified by immunochemical staining and transmission electron microscopy. Nucleic acid levels of HRV-C and HBoV in 3D cells at designated time points were quantitated by real-time polymerase chain reaction (PCR). Levels of cytokines, whose secretion was induced by the viruses, were measured by ELISA.

RESULTS

Properties of bronchial-like tissues, such as the expression of biomarkers CK5, ZO-1, and PCK, and the development of cilium-like protuberances indicative of the human respiration tract, were observed in 3D-cultured human airway epithelial (HAE) cultures, but not in monolayer-cultured cells. Nucleic acid levels of HRV-C and HBoV and levels of virus-induced cytokines were also measured using the 3D culture system.

CONCLUSION

Our data provide a preliminary indication that the 3D culture model of primary epithelia using a Matrigel scaffold in vitro can be used to propagate HRV-C and HBoV.

Rhinovirus - not just the common cold

Rhinoviruses (RV) are ubiquitous respiratory tract pathogens. They affect both the upper and lower respiratory tract and cause colds but have also been associated with wheezing, asthma exacerbations and pneumonia. New blood transcription profiling techniques of the host immune response are becoming available to characterise the pathogenesis of RV in humans. This review will outline the clinical impact of RVs in children.

Persistent activation of interlinked type 2 airway epithelial gene networks in sputum-derived cells from aeroallergen-sensitized symptomatic asthmatics

Atopic asthma is a persistent disease characterized by intermittent wheeze and progressive loss of lung function. The disease is thought to be driven primarily by chronic aeroallergen-induced type 2-associated inflammation. However, the vast majority of atopics do not develop asthma despite ongoing aeroallergen exposure, suggesting additional mechanisms operate in conjunction with type 2 immunity to drive asthma pathogenesis. We employed RNA-Seq profiling of sputum-derived cells to identify gene networks operative at baseline in house dust mite-sensitized (HDM^S) subjects with/without wheezing history that are characteristic of the ongoing asthmatic state. The expression of type 2 effectors (IL-5, IL-13) was equivalent in both cohorts of subjects. However, in HDM^S-wheezers they were associated with upregulation of two coexpression modules comprising multiple type 2- and epithelial-associated genes. The first module was interlinked by the hubs EGFR, ERBB2, CDH1 and IL-13. The second module was associated with CDHR3 and mucociliary clearance genes. Our findings provide new insight into the molecular mechanisms operative at baseline in the airway mucosa in atopic asthmatics undergoing natural aeroallergen exposure, and suggest that susceptibility to asthma amongst these subjects involves complex interactions between type 2- and epithelial-associated gene networks, which are not operative in equivalently sensitized/exposed atopic non-asthmatics.

Classification of Pediatric Asthma: From Phenotype Discovery to Clinical Practice

Advances in big data analytics have created an opportunity for a step change in unraveling mechanisms underlying the development of complex diseases such as asthma, providing valuable insights that drive better diagnostic decision-making in clinical practice, and opening up paths to individualized treatment plans. However, translating findings from data-driven analyses into meaningful insights and actionable solutions requires approaches and tools which move beyond mining and patterning longitudinal data. The purpose of this review is to summarize recent advances in phenotyping of asthma, to discuss key hurdles currently hampering the translation of phenotypic variation into mechanistic insights and clinical setting, and to suggest potential solutions that may address these limitations and accelerate moving discoveries into practice. In order to advance the field of phenotypic discovery, greater focus should be placed on investigating the extent of within-phenotype variation. We advocate a more cautious modeling approach by "supervising" the findings to delineate more precisely the characteristics of the individual trajectories assigned to each phenotype. Furthermore, it is important to employ different methods within a study to compare the stability of derived phenotypes, and to assess the immutability of individual assignments to phenotypes. If we are to make a step change toward precision (stratified or personalized) medicine and capitalize on the available big data assets, we have to develop genuine cross-disciplinary collaborations, wherein data scientists who turn data into information using algorithms and machine learning, team up with medical professionals who provide deep insights on specific subjects from a clinical perspective.

Clinical approaches towards asthma and chronic obstructive pulmonary disease based on the heterogeneity of disease pathogenesis

Asthma and chronic obstructive pulmonary disease (COPD) are each heterogeneous disease classifications that include several clinical and pathophysiological phenotypes. This heterogeneity complicates characterization of each disease and, in some cases, hinders the selection of appropriate treatment. Therefore, in recent years, emphasis has been placed on improving our understanding of the various phenotypes of asthma and of COPD and identifying biomarkers for each phenotype. Likewise, the concept of the endotype has been gaining acceptance; an endotype is a disease subtype that is defined by unique or distinctive functional or pathophysiological mechanisms. Endotypes of asthma or COPD may be primarily characterized by increased susceptibility to type 2 inflammation, increased susceptibility to viral infections, bacterial colonization or impaired lung development. The 'Dutch hypothesis' is as follows: gene variants underlying particular endotypes interact with detrimental environmental stimuli (e.g. smoking, viral infection and air pollution) and contribute to the ultimate development of asthma, COPD or both. Novel approaches that involve multidimensional assessment should facilitate identification and management of the components that generate this heterogeneity. Ultimately, patients with chronic inflammatory lung diseases may be treated based on these endotypes as determined by the respective biomarkers that correspond to individual endotypes instead of on disease labels such as asthma, COPD or even asthma-COPD overlap syndrome (ACOS).

Rhinovirus Viremia in Patients Hospitalized With Community-Acquired Pneumonia

Background

Rhinoviruses (RVs) are ubiquitous respiratory pathogens that often cause mild or subclinical infections. Molecular detection of RVs from the upper respiratory tract can be prolonged, complicating etiologic association in persons with severe lower respiratory tract infections. Little is known about RV viremia and its value as a diagnostic indicator in persons hospitalized with community-acquired pneumonia (CAP).

Methods

Sera from RV-positive children and adults hospitalized with CAP were tested for RV by real-time reverse-transcription polymerase chain reaction. Rhinovirus species and type were determined by partial genome sequencing.

Results

Overall, 57 of 570 (10%) RV-positive patients were viremic, and all were children aged <10 years (n = 57/375; 15.2%). Although RV-A was the most common RV species detected from respiratory specimens (48.8%), almost all viremias were RV-C (98.2%). Viremic patients had fewer codetected pathogens and were more likely to have chest retractions, wheezing, and a history of underlying asthma/reactive airway disease than patients without viremia.

Conclusions

More than 1 out of 7 RV-infected children aged <10 years hospitalized with CAP were viremic. In contrast with other RV species, RV-C infections were highly associated with viremia and were usually the only respiratory pathogen identified, suggesting that RV-C viremia may be an important diagnostic indicator in pediatric pneumonia.

Rhinovirus Biology, Antigenic Diversity, and Advancements in the Design of a Human Rhinovirus Vaccine

Human rhinovirus (HRV) remains a leading cause of several human diseases including the common cold. Despite considerable research over the last 60 years, development of an effective vaccine to HRV has been viewed by many as unfeasible due, in part, to the antigenic diversity of circulating HRVs in nature. Over 150 antigenically distinct types of HRV are currently known which span three species: HRV A, HRV B, and HRV C. Early attempts to develop a rhinovirus vaccine have shown that inactivated HRV is capable of serving as a strong immunogen and inducing neutralizing antibodies. Yet, limitations to virus preparation and recovery, continued identification of antigenic variants of HRV, and logistical challenges pertaining to preparing a polyvalent preparation of the magnitude required for true efficacy against circulating rhinoviruses continue to prove a daunting challenge. In this review, we describe HRV biology, antigenic diversity, and past and present advances in HRV vaccine design.

Epidemiological analysis and follow-up of human rhinovirus infection in children with asthma exacerbation

To determine the prevalence of human rhinovirus (HRV) infection in children with acute asthma exacerbations, investigation of HRV viral load and severity of asthma exacerbations is also required. Nasopharyngeal aspirates and swabs were collected and assessed for respiratory viruses. HRV-positive samples were sequenced to identify types and determine viral load. Outpatients with asthma exacerbations underwent follow-up evaluations, their swabs were collected and clinical outcomes were recorded at their next clinic visit 4 weeks later. One hundred forty-three inpatients and 131 outpatients, including 88 patients with asthma exacerbations and 43 controls with stable asthma were recruited. HRV-A was mainly detected in September and February (45.5% and 33.3%, respectively), while HRV-C was mainly detected in November and April (70.0% and 55.6%, respectively). HRV-C was the primary type and was primarily found in inpatients with severe asthma exacerbations. HRV-A viral load in the group of inpatients with severe exacerbations was higher than in the mild and moderate groups (P < 0.001 and P = 0.022). The HRV-A viral load of both inpatients and outpatients was higher than that of HRV-C (P < 0.001 and P = 0.036). The main genotypes were HRV-C53 and HRV-A20 among inpatients, and this genotype caused more severe clinical manifestations. HRV persisted for no more than 4 weeks, and their symptoms or signs of disease were well-controlled well. HRV-C was most frequently detected in asthma exacerbations. HRV-A with high viral load led to severe asthma exacerbations.

Role of viral infections in the development and exacerbation of asthma in children

Viral infections are closely linked to wheezing illnesses in children of all ages. Respiratory syncytial virus (RSV) is the main causative agent of bronchiolitis, whereas rhinovirus (RV) is most commonly detected in wheezing children thereafter. Severe respiratory illness induced by either of these viruses is associated with subsequent development of asthma, and the risk is greatest for young children who wheeze with RV infections. Whether viral illnesses actually cause asthma is the subject of intense debate. RSV-induced wheezing illnesses during infancy influence respiratory health for years. There is definitive evidence that RSV-induced bronchiolitis can damage the airways to promote airway obstruction and recurrent wheezing. RV likely causes less structural damage and yet is a significant contributor to wheezing illnesses in young children and in the context of asthma. For both viruses, interactions between viral virulence factors, personal risk factors (eg, genetics), and environmental exposures (eg, airway microbiome) promote more severe wheezing illnesses and the risk for progression to asthma. In addition, allergy and asthma are major risk factors for more frequent and severe RV-related illnesses. Treatments that inhibit inflammation have efficacy for RV-induced wheezing, whereas the anti-RSV mAb palivizumab decreases the risk of severe RSV-induced illness and subsequent recurrent wheeze. Developing a greater understanding of personal and environmental factors that promote more severe viral illnesses might lead to new strategies for the prevention of viral wheezing illnesses and perhaps reduce the subsequent risk for asthma.

Novel therapeutic approaches to simultaneously target rhinovirus infection and asthma/COPD pathogenesis

Rhinoviruses are exclusive respiratory pathogens and the etiological agents of the common cold. These viruses are increasingly reported to cause exacerbations of asthma and chronic obstructive pulmonary disease (COPD). Here, we review the role of rhinovirus infections in the pathogenesis of asthma and COPD and we discuss the current and potential future treatments. We propose that, in order to prevent exacerbations, the design of novel therapeutics should focus on directly acting antivirals but also include the design of drugs that simultaneously inhibit viral replication and alleviate symptoms of asthma and COPD.

Microbes and the Role of Antibiotic Treatment for Wheezy Lower Respiratory Tract Illnesses in Preschool Children

PURPOSE OF REVIEW

Antibiotics are commonly used to treat wheezy lower respiratory tract illnesses in preschoolers, although these infections have been traditionally thought to be predominantly of viral origin. Our purpose is to review recent research pertaining to the role of antibiotics in lower respiratory tract illnesses and on subsequent asthma development, as well as the possible mechanisms of their effects.

RECENT FINDINGS

Increasing evidence suggests that asthma pathogenesis is associated with events during infancy and early childhood, particularly respiratory tract infections. While viruses are frequently detected in children with lower respiratory tract infections, the presence of potentially pathogenic bacteria is also often detected and may play a role in asthma pathogenesis. Recent evidence suggests that use of macrolides, particularly azithromycin, may decrease the risk of and duration of lower respiratory tract illnesses and prevent future episodes in specific high-risk populations. Infants and preschoolers who have wheezy lower respiratory tract illnesses have a higher risk of asthma development. Alterations in the microbiome are thought to be influential. While several recent studies identify azithromycin as a therapeutic option in these illnesses, additional research is needed.

The role of respiratory tract infections and the microbiome in the development of asthma: A narrative review

Asthma is a common disease in childhood, and might predispose for chronic obstructive respiratory morbidity in adolescence and adulthood. Various early-life risk factors might influence the risk of wheezing, asthma, and lower lung function in childhood. Cohort studies demonstrated that lower respiratory tract infections in the first years of life are associated with an increased risk of wheezing and asthma, while the association with lung function is less clear. Additionally, the gut and airway microbiome might influence the risk of wheezing and asthma. The interaction between respiratory tract infections and the microbiome complicates studies of their associations with wheezing, asthma, and lung function. Furthermore, the causality behind these observations is still unclear, and several other factors such as genetic susceptibility and the immune system might be of importance. This review is focused on the association of early-life respiratory tract infections and the microbiome with wheezing, asthma, and lung function, it is possible influencing factors and perspectives for future studies.

Genetic association of the functional CDHR3 genotype with early-onset adult asthma in Japanese populations

BACKGROUND

Recent studies have demonstrated that a coding SNP (rs6967330, Cys529→Tyr) in cadherin-related family member 3 (CDHR3), which was previously associated with wheezing illness and hospitalizations in infancy, could support efficient human rhinovirus C (RV-C) entry and replication. Here, we sought to examine the genetic contribution of this variant to the development of adult asthma.

METHODS

We performed a candidate gene case-control association study of 2 independent Japanese populations (a total of 3366 adults). The odds ratios (ORs) for association of the A allele at rs6967330 with adult asthma were calculated according to age at onset of asthma. In addition, the effect of the CDHR3 genotype on the development of specific asthma phenotypes was examined.

RESULTS

The A allele was associated with asthma (OR = 1.56; Mantel-Haenszel p = 0.0040) when the analysis was limited to patients with early-onset adult asthma. In addition, when the analysis was limited to atopic individuals, a stronger association of the CDHR3 variant with early-onset asthma was found, and interaction of the CDHR3 genotype with atopy was demonstrated. Finally, a significant association of this variant was specifically found with a phenotype of asthma characterized by atopy, early-onset, and lower lung function.

CONCLUSIONS

Our study supports the concept that the CDHR3 variant is an important susceptibility factor for severe adult asthma in individuals who develop the disease in early life. The interaction between the CDHR3 variant and atopy indicates that genetic predisposition to early respiratory viral infection is combined with atopy in promoting asthma.