[Expression of interferon-λ1 in respiratory epithelial cells in children with human rhinovirus infection]

OBJECTIVE

To study the expression of interferon-λ1 (IFN-λ1) in respiratory epithelial cells in children with human rhinovirus (HRV) infection.

METHODS

Sputum samples and nasopharyngeal swabs were collected from the children who were hospitalized due to acute respiratory infection from February to October, 2017. Bacterial culture was performed, and nucleic acid test was performed for 11 respiratory pathogens. A total of 90 children with positive HRV alone were enrolled as the HRV infection group, and 95 children with positive respiratory syncytial virus (RSV) alone were enrolled as the RSV infection group. A total of 50 healthy children who underwent outpatient physical examination during the same period of time and had negative results for all pathogen tests were enrolled as the healthy control group. Nasopharyngeal swabs were collected from all groups, and quantitative real-time PCR was used to measure viral load and the mRNA expression of IFN-λ1.

RESULTS

In the HRV infection group, there was no significant difference in the mRNA expression of IFN-λ1 between boys and girls and across all age groups (P>0.05). In the HRV infection group, there was no correlation between the mRNA expression of IFN-λ1 and HRV load (P>0.05). The mRNA expression of IFN-λ1 in the HRV infection group was significantly higher than that in the healthy control group (P<0.05), but significantly lower than that in the RSV infection group (P<0.05).

CONCLUSIONS

HRV can induce the expression of IFN-λ1 in respiratory epithelial cells, suggesting that IFN-λ1 may play an important role in anti-HRV infection in children.

[Expression of interferon-λ1 in respiratory epithelial cells in children with human rhinovirus infection]

OBJECTIVE

To study the expression of interferon-λ1 (IFN-λ1) in respiratory epithelial cells in children with human rhinovirus (HRV) infection.

METHODS

Sputum samples and nasopharyngeal swabs were collected from the children who were hospitalized due to acute respiratory infection from February to October, 2017. Bacterial culture was performed, and nucleic acid test was performed for 11 respiratory pathogens. A total of 90 children with positive HRV alone were enrolled as the HRV infection group, and 95 children with positive respiratory syncytial virus (RSV) alone were enrolled as the RSV infection group. A total of 50 healthy children who underwent outpatient physical examination during the same period of time and had negative results for all pathogen tests were enrolled as the healthy control group. Nasopharyngeal swabs were collected from all groups, and quantitative real-time PCR was used to measure viral load and the mRNA expression of IFN-λ1.

RESULTS

In the HRV infection group, there was no significant difference in the mRNA expression of IFN-λ1 between boys and girls and across all age groups (P>0.05). In the HRV infection group, there was no correlation between the mRNA expression of IFN-λ1 and HRV load (P>0.05). The mRNA expression of IFN-λ1 in the HRV infection group was significantly higher than that in the healthy control group (P<0.05), but significantly lower than that in the RSV infection group (P<0.05).

CONCLUSIONS

HRV can induce the expression of IFN-λ1 in respiratory epithelial cells, suggesting that IFN-λ1 may play an important role in anti-HRV infection in children.

Oxidative Stress Attenuates TLR3 Responsiveness and Impairs Anti-viral Mechanisms in Bronchial Epithelial Cells From COPD and Asthma Patients

COPD and asthma exacerbations are commonly triggered by rhinovirus infection. Potentially promoting exacerbations, impaired anti-viral signaling and attenuated viral clearance have been observed in diseased bronchial epithelium. Oxidative stress is a feature of inflammation in asthma and COPD and is prominent during exacerbations. It is not known whether oxidative stress affects the anti-viral signaling capacity. Bronchial epithelial cells from asthmatic and COPD donors were infected with rhinovirus or treated with the oxidative stressor H₂O₂ followed by exposure to the synthetic viral replication intermediate poly(I:C). Poly(I:C) was used to ascertain a constant infection-like burden. Gene and protein levels of antioxidants as well as anti-viral responses were measured 3 and 24 h post poly(I:C) exposure. Rhinovirus infection and poly(I:C) stimulation induced protein levels of the antioxidants SOD1 and SOD2. In asthmatic bronchial epithelial cells pre-treatment with H₂O₂ dose-dependently decreased the antioxidant response to poly(I:C), suggesting exaggerated oxidative stress. Further, poly(I:C)-induced IFNβ gene expression was reduced after pre-treatment with H₂O₂. This epithelial effect was associated with a reduced expression of the pattern recognition receptors RIG-I, MDA5 and TLR3 both on gene and protein level. Pre-treatment with H₂O₂ did not alter antioxidant responses in COPD bronchial epithelial cells and, more modestly than in asthma, reduced poly(I:C)-induced IFNβ gene expression. Knockdown of TLR3 but not RIG-I/MDA5 abrogated impairment of poly(I:C)-induced IFNβ gene expression by H₂O₂. We developed a method by which we could demonstrate that oxidative stress impairs anti-viral signaling in bronchial epithelial cells from asthmatic and COPD patients, most pronounced in asthma. The impairment apparently reflects reduced responsiveness of TLR3. These present findings shed light on molecular mechanisms potentially causing reduced interferon responses to rhinovirus infection at exacerbations in asthma and COPD. Together, our findings suggest a possible self-perpetuating vicious cycle underlying recurrent exacerbations, leading to an impaired anti-viral response, which in turn leads to viral-induced exacerbations, causing more airway inflammation.

Identification of a Novel Inhibitor of Human Rhinovirus Replication and Inflammation in Airway Epithelial Cells

Human rhinovirus (RV), the major cause of the common cold, triggers the majority of acute airway exacerbations in patients with asthma and chronic obstructive pulmonary disease. Nitric oxide, and the related metabolite S-nitrosoglutathione, are produced in the airway epithelium via nitric oxide synthase (NOS) 2 and have been shown to function in host defense against RV infection. We hypothesized that inhibitors of the S-nitrosoglutathione-metabolizing enzyme, S-nitrosoglutathione reductase (GSNOR), might potentiate the antiviral properties of airway-derived NOS2. Using in vitro models of RV-A serotype 16 (RV-A16) and mNeonGreen-H1N1pr8 infection of human airway epithelial cells, we found that treatment with a previously characterized GSNOR inhibitor (4-[[2-[[(3-cyanophenyl)methyl]thio]-4-oxothieno-[3,2-d]pyrimidin-3(4H)-yl]methyl]-benzoic acid; referred to as C3m) decreased RV-A16 replication and expression of downstream proinflammatory and antiviral mediators (e.g., RANTES [regulated upon activation, normal T cell expressed and secreted], CXCL10, and Mx1), and increased Nrf2 (nuclear factor erythroid 2-related factor 2)-dependent genes (e.g., SQSTM1 and TrxR1). In contrast, C3m had no effect on influenza virus H1N1pr8 replication. Moreover, a structurally dissimilar GSNOR inhibitor (N6022) did not alter RV replication, suggesting that the properties of C3m may be specific to rhinovirus owing to an off-target effect. Consistent with this, C3m antiviral effects were not blocked by either NOS inhibition or GSNOR knockdown but appeared to be mediated by reduced intercellular adhesion molecule 1 transcription and increased shedding of soluble intercellular adhesion molecule 1 protein. Collectively these data show that C3m has novel antirhinoviral properties that may synergize with, but are unrelated to, its GSNOR inhibitor activity.

Loss of adaptive capacity in asthmatic patients revealed by biomarker fluctuation dynamics after rhinovirus challenge

Asthma is a dynamic disease, in which lung mechanical and inflammatory processes interact in a complex manner, often resulting in exaggerated physiological, in particular, inflammatory responses to exogenous triggers. We hypothesize that this may be explained by respiratory disease-related systems instability and loss of adaptability to changing environmental conditions, manifested in highly fluctuating biomarkers and symptoms. Using time series of inflammatory (eosinophils, neutrophils, FeNO), clinical and lung function biomarkers (PEF, FVC,FEV₁), we estimated this loss of adaptive capacity (AC) during an experimental rhinovirus infection in 24 healthy and asthmatic human volunteers. Loss of AC was estimated by comparing similarities between pre- and post-challenge time series. Unlike healthy participants, the asthmatic’s post-viral-challenge state resembled more other rhinovirus-infected asthmatics than their own pre-viral-challenge state (hypergeometric-test: p=0.029). This reveals loss of AC and supports the concept that in asthma, biological processes underlying inflammatory and physiological responses are unstable, contributing to loss of control.

Multi-season analyses of causative pathogens in children hospitalized with asthma exacerbation

BACKGROUND

Respiratory viral and mycoplasma infections are associated with childhood asthma exacerbations. Here, we explored epidemiologic profile of causative pathogens and possible factors for exacerbation in a single center over a three-year period.

METHODS

Hospitalized asthmatic children with attack aged 6 months-17 years were recruited between 2012 and 2015 (n = 216). Nasopharyngeal mucosa cell samples were collected from the participants and examined by reverse transcription-polymerase chain reaction to detect rhinovirus (RV), respiratory syncytial virus (RSV), enterovirus (EV), parainfluenza virus (PIV), Mycoplasma pneumoniae, and others. Clinical features, laboratory data, asthma exacerbation intensity, and asthma severity were compared among participants. Epidemiologic profile of causative pathogens and possible factors for exacerbation were explored.

RESULTS

Viruses and/or Mycoplasma pneumoniae were detected in 75% of the participants. Rhinovirus (48%) was the most commonly detected virus in the participants with single infection, followed by RSV (6%). The median age at admission in the RV group was significantly higher than that in the RSV group. Insufficient asthma control and allergen sensitization were significantly related to RV-associated asthma exacerbation. There was no seasonality of pathogen types associated with asthma exacerbation although a sporadic prevalence of EV-D68 was observehinovirud. Rhinovirus were repeatedly detected in multiple admission cases.

CONCLUSION

Our three-year analysis revealed that patients with RV infection were significantly prone to repeated RV infection in the subsequent exacerbation and good asthma control could prevent RV-associated asthma development and exacerbation. Multiple-year monitoring allowed us to comprehend the profile of virus- and/or mycoplasma-induced asthma exacerbation.

Picornaviruses and RNA Metabolism: Local and Global Effects of Infection

Due to the limiting coding capacity for members of the Picornaviridae family of positive-strand RNA viruses, their successful replication cycles require complex interactions with host cell functions. These interactions span from the down-modulation of many aspects of cellular metabolism to the hijacking of specific host functions used during viral translation, RNA replication, and other steps of infection by picornaviruses, such as human rhinovirus, coxsackievirus, poliovirus, foot-and-mouth disease virus, enterovirus D-68, and a wide range of other human and nonhuman viruses. Although picornaviruses replicate exclusively in the cytoplasm of infected cells, they have extensive interactions with host cell nuclei and the proteins and RNAs that normally reside in this compartment of the cell. This review will highlight some of the more recent studies that have revealed how picornavirus infections impact the RNA metabolism of the host cell posttranscriptionally and how they usurp and modify host RNA binding proteins as well as microRNAs to potentiate viral replication.

Distinct nasal airway bacterial microbiotas differentially relate to exacerbation in pediatric patients with asthma

BACKGROUND

In infants, distinct nasopharyngeal bacterial microbiotas differentially associate with the incidence and severity of acute respiratory tract infection and childhood asthma development.

OBJECTIVE

We hypothesized that distinct nasal airway microbiota structures also exist in children with asthma and relate to clinical outcomes.

METHODS

Nasal secretion samples (n = 3122) collected after randomization during the fall season from children with asthma (6-17 years, n = 413) enrolled in a trial of omalizumab (anti-IgE) underwent 16S rRNA profiling. Statistical analyses with exacerbation as the primary outcome and rhinovirus infection and respiratory illnesses as secondary outcomes were performed. Using A549 epithelial cells, we assessed nasal isolates of Moraxella, Staphylococcus, and Corynebacterium species for their capacity to induce epithelial damage and inflammatory responses.

RESULTS

Six nasal airway microbiota assemblages, each dominated by Moraxella, Staphylococcus, Corynebacterium, Streptococcus, Alloiococcus, or Haemophilus species, were observed. Moraxella and Staphylococcus species-dominated microbiotas were most frequently detected and exhibited temporal stability. Nasal microbiotas dominated by Moraxella species were associated with increased exacerbation risk and eosinophil activation. Staphylococcus or Corynebacterium species-dominated microbiotas were associated with reduced respiratory illness and exacerbation events, whereas Streptococcus species-dominated assemblages increased the risk of rhinovirus infection. Nasal microbiota composition remained relatively stable despite viral infection or exacerbation; only a few taxa belonging to the dominant genera exhibited relative abundance fluctuations during these events. In vitro, Moraxella catarrhalis induced significantly greater epithelial damage and inflammatory cytokine expression (IL-33 and IL-8) compared with other dominant nasal bacterial isolates tested.

CONCLUSION

Distinct nasal airway microbiotas of children with asthma relate to the likelihood of exacerbation, rhinovirus infection, and respiratory illnesses during the fall season.

Rhinovirus-16 induced temporal interferon responses in nasal epithelium links with viral clearance and symptoms

BACKGROUND

The temporal in vivo response of epithelial cells to a viral challenge and its association with viral clearance and clinical outcomes has been largely unexplored in asthma.

OBJECTIVE

To determine gene expression profiles over time in nasal epithelial cells (NECs) challenged in vivo with rhinovirus-16 (RV16) and compare to nasal symptoms and viral clearance.

METHODS

Patients with stable mild to moderate asthma (n = 20) were challenged intranasally with RV16. Nasal brush samples for RNA sequencing were taken 7 days prior to infection and 3, 6 and 14 days post-infection, and blood samples 4 days prior to infection and day 6 post-infection. Viral load was measured in nasal lavage fluid at day 3, 6 and 14.

RESULTS

Top differentially (>2.5-fold increase) expressed gene sets in NECs post-RV16 at days 3 and 6, compared with baseline, were interferon alpha and gamma response genes. Patients clearing the virus within 6 days (early resolvers) had a significantly increased interferon response at day 6, whereas those having cleared the virus by day 14 (late resolvers) had significantly increased responses at day 3, 6 and 14. Interestingly, patients not having cleared the virus by day 14 (non-resolvers) had no enhanced interferon responses at any of these days. The daily Cold Symptom Scores (CSS) peaked at days 3 to 5 and correlated positively with interferon response genes at day 3 (R = 0.48), but not at other time-points. Interferon response genes were also enhanced in blood at day 6 after RV16 challenge.

CONCLUSION AND CLINICAL RELEVANCE

This study shows that viral load and clearance varies markedly over time in mild to moderate asthma patients exposed to a fixed RV16 dose. The host's nasal interferon response to RV16 at day 3 is associated with upper respiratory tract symptoms. The temporal interferon response in nasal epithelium associates with viral clearance in the nasal compartment.

Characteristics of Hospitalized Rhinovirus-Associated Community-Acquired Pneumonia in Children, Finland, 2003-2014

Background: Rhinovirus (RV) is the most common cause of respiratory tract infections in children but, still, the clinical characteristics of RV-associated pneumonia have not been sufficiently investigated.

Methods: We identified children and adolescents younger than 18 years of age treated for community-acquired pneumonia as inpatients at the Turku University Hospital from 2003 to 2014 and analyzed for RV by PCR of a respiratory tract specimen. We collected the data from medical records and compared RV-positive children with RV-negative children.

Results: Of the study population of 313 children with pneumonia who were studied for RV, it was detected in 82 (26%). RV-positive children were younger (median age 2.6 years, interquartile range [IQR] 1.1–4.6 vs. 3.5 years, IQR 1.7–8.3, p = 0.002) and they had more often a history of preterm birth (16% vs. 5%, adjusted odds ratio 2.89, 95% confidence interval 1.21–6.92, p = 0.017) than RV-negative children. RV-positive children had a higher median white blood cell count than RV-negative children at presentation with pneumonia. The signs, symptoms, and severity of pneumonia were mostly similar in RV-positive and RV-negative children.

Conclusions: RV was frequently detected in young children hospitalized with community-acquired pneumonia. We identified premature birth as a factor associated with RV-positive pneumonia. The clinical features of pneumonia did not clearly differ between RV-positive and RV-negative children. Further studies are needed to clarify the clinical significance of detection of RV in children with pneumonia.

Risk factors and patterns of household clusters of respiratory viruses in rural Nepal

Viral pneumonia is an important cause of death and morbidity among infants worldwide. Transmission of non-influenza respiratory viruses in households can inform preventative interventions and has not been well-characterised in South Asia. From April 2011 to April 2012, household members of pregnant women enrolled in a randomised trial of influenza vaccine in rural Nepal were surveyed weekly for respiratory illness until 180 days after birth. Nasal swabs were tested by polymerase chain reaction for respiratory viruses in symptomatic individuals. A transmission event was defined as a secondary case of the same virus within 14 days of initial infection within a household. From 555 households, 825 initial viral illness episodes occurred, resulting in 79 transmission events. The overall incidence of transmission was 1.14 events per 100 person-weeks. Risk of transmission incidence was associated with an index case age 1-4 years (incidence rate ratio (IRR) 2.35; 95% confidence interval (CI) 1.40-3.96), coinfection as initial infection (IRR 1.94; 95% CI 1.05-3.61) and no electricity in household (IRR 2.70; 95% CI 1.41-5.00). Preventive interventions targeting preschool-age children in households in resource-limited settings may decrease the risk of transmission to vulnerable household members, such as young infants.

CDHR3 Asthma-Risk Genotype Affects Susceptibility of Airway Epithelium to Rhinovirus C Infections

CDHR3 (cadherin-related family member 3) is a transmembrane protein that is highly expressed in airway epithelia and the only known receptor for rhinovirus C (RV-C). A CDHR3 SNP (rs6967330) with G to A base change has been linked to severe exacerbations of asthma and increased susceptibility to RV-C infections in young children. The goals of this study were to determine the subcellular localization of CDHR3 and to test the hypothesis that CDHR3 asthma-risk genotype affects epithelial cell function and susceptibility to RV-C infections of the airway epithelia. We used immunofluorescence imaging, Western blot analysis, and transmission electron microscopy to show CDHR3 subcellular localization in apical cells, including expression in the cilia of airway epithelia. Polymorphisms in CDHR3 rs6967330 locus (G→A) that were previously associated with childhood asthma were related to differences in CDHR3 expression and epithelial cell function. The rs6967330 A allele was associated with higher overall protein expression and RV-C binding and replication compared with the rs6967330 G allele. Furthermore, the rs6967330 A allele was associated with earlier ciliogenesis and higher FOXJ1 expression. Finally, CDHR3 genotype had no significant effects on membrane integrity or ciliary beat function. These findings provide information on the subcellular localization and possible functions of CDHR3 in the airways and link CDHR3 asthma-risk genotype to increased RV-C binding and replication.

Genetic diversity of respiratory enteroviruses and rhinoviruses in febrile adults, Singapore, 2007-2013

To understand the genetic diversity and patterns of circulation of rhinoviruses (RV) and enteroviruses (EV) in Singapore, we retrospectively screened 2950 nasal swab samples collected from adults presenting to primary care services with signs of febrile illness in Singapore during 2007‐2013 using sequencing and phylogenetic methods. Through sequencing and phylogenetic analysis, our results show the year‐round circulation of the three rhinovirus species, A, B, and C. A diverse set of RV/EV serotypes were detected in Singapore with a predominance of RV‐A in all years, whereas serotypes EV‐C A21 and EV‐D68 were only sporadically detected. This study highlights the previously unrecognized diversity and burden in the adult population in Singapore.

Effect of Geographic Isolation on the Nasal Virome of Indigenous Children

The influence of living in small remote villages on the diversity of viruses in the nasal mucosa was investigated in three Colombian villages with very different levels of geographic isolation. Metagenomic analysis was used to characterize viral nucleic acids in nasal swabs from 63 apparently healthy young children. Sequences from human virus members of the families Anelloviridae, Papillomaviridae, Picornaviridae, Herpesviridae, Polyomaviridae, Adenoviridae, and Paramyxoviridae were detected in decreasing proportions of children. The number of papillomavirus infections detected was greater among Hispanic children most exposed to outside contacts, while anellovirus infections were more common in the isolated indigenous villages. The diversity of the other human viruses detected did not differ among the villages. Closely related variants of rhinovirus A or B were identified in 2 to 4 children from each village, reflecting ongoing transmission clusters. Genomes of viruses not currently known to infect humans, including members of the families Parvoviridae, Partitiviridae, Dicistroviridae, and Iflaviridae and circular Rep-encoding single-stranded DNA (CRESS-DNA) virus, were also detected in nasal swabs, possibly reflecting environmental contamination from insect, fungal, or unknown sources. Despite the high levels of geographic and cultural isolation, the overall diversity of human viruses in the nasal passages of children was not reduced in highly isolated indigenous villages, indicating ongoing exposure to globally circulating viruses.IMPORTANCE Extreme geographic and cultural isolation can still be found in some indigenous South American villages. Such isolation may be expected to limit the introduction of otherwise common and widely distributed viruses. Very small population sizes may also result in rapid local viral extinction due to a lack of seronegative subjects to maintain transmission chains for rapidly cleared viruses. We compared the viruses in the nasal passages of young children in three villages with increasing levels of geographic isolation. We found that isolation did not reduce the overall diversity of viral infections. Multiple infections with nearly identical rhinoviruses could be detected within each village, likely reflecting recent viral introductions and transmission clusters among epidemiologically linked members of these very small communities. We conclude that, despite their geographic isolation, remote indigenous villages show evidence of ongoing exposure to globally circulating viruses.

Cryo-EM structure of pleconaril-resistant rhinovirus-B5 complexed to the antiviral OBR-5-340 reveals unexpected binding site

Viral inhibitors, such as pleconaril and vapendavir, target conserved regions in the capsids of rhinoviruses (RVs) and enteroviruses (EVs) by binding to a hydrophobic pocket in viral capsid protein 1 (VP1). In resistant RVs and EVs, bulky residues in this pocket prevent their binding. However, recently developed pyrazolopyrimidines inhibit pleconaril-resistant RVs and EVs, and computational modeling has suggested that they also bind to the hydrophobic pocket in VP1. We studied the mechanism of inhibition of pleconaril-resistant RVs using RV-B5 (1 of the 7 naturally pleconaril-resistant rhinoviruses) and OBR-5-340, a bioavailable pyrazolopyrimidine with proven in vivo activity, and determined the 3D-structure of the protein-ligand complex to 3.6 Å with cryoelectron microscopy. Our data indicate that, similar to other capsid binders, OBR-5-340 induces thermostability and inhibits viral adsorption and uncoating. However, we found that OBR-5-340 attaches closer to the entrance of the pocket than most other capsid binders, whose viral complexes have been studied so far, showing only marginal overlaps of the attachment sites. Comparing the experimentally determined 3D structure with the control, RV-B5 incubated with solvent only and determined to 3.2 Å, revealed no gross conformational changes upon OBR-5-340 binding. The pocket of the naturally OBR-5-340-resistant RV-A89 likewise incubated with OBR-5-340 and solved to 2.9 Å was empty. Pyrazolopyrimidines have a rigid molecular scaffold and may thus be less affected by a loss of entropy upon binding. They interact with less-conserved regions than known capsid binders. Overall, pyrazolopyrimidines could be more suitable for the development of new, broadly active inhibitors.

Most commonly isolated viruses in asthma exacerbation and their correlation with eosinophil and total serum immunoglobulin E levels

BACKGROUND

Asthma exacerbations are still a cause of hospitalization at the Emergency Department. The triggers of asthma exacerbations include allergens and infections -mostly viral-. The objective of this study was to establish the relationship between viruses detected during an asthma exacerbation and eosinophil and serum immunoglobulin E (IgE) levels in pediatric patients.

POPULATION AND METHODS

Cross-sectional. analytical study. Children aged 5-15 years seen at the Pediatric Emergency Department with an asthma exacerbation in the period between March 2013 and February 2016 were included. Viral ribonucleic acid was extracted from nasopharyngeal aspirates using the CLART Pneumo Vir kit. Eosinophil levels were measured in peripheral blood and total IgE levels, in serum. Eosinophilia was defined as a count ≥ 0.4 x 103/ mm3 and high IgE. as a level ≥ 350 IU/L. The Pearson's correlation was carried out. A value of p ≤ 0.05 was considered significant.

RESULTS

Out of 211 children with asthma exacerbation, a virus was isolated in 20%. The most commonly isolated viruses were rhinovirus. enterovirus, and respiratory syncytial virus. A correlation of 0.89 was established between eosinophil and total serum IgE levels in children with asthma exacerbation and rhinovirus, with a p value of 0.0001.

CONCLUSIONS

Rhinovirus, enterovirus, and respiratory syncytial virus were the most common viruses in asthma exacerbations in children younger than 15 years. A correlation was established between eosinophil and IgE levels in the presence of rhinovirus.

Molecular Subtyping of Human Rhinovirus in Children from Three Sub-Saharan African Countries

The pathogenesis of human rhinovirus (HRV) during severe respiratory disease remains undefined; thus, we aimed to explore the relationship between the HRV molecular subtyping results obtained during severe and asymptomatic childhood infections. Nasopharyngeal/oropharyngeal swabs from children (1 to 59 months of age) hospitalized with pneumonia and from age-frequency-matched controls were collected between August 2011 and August 2013.

The pathogenesis of human rhinovirus (HRV) during severe respiratory disease remains undefined; thus, we aimed to explore the relationship between the HRV molecular subtyping results obtained during severe and asymptomatic childhood infections. Nasopharyngeal/oropharyngeal swabs from children (1 to 59 months of age) hospitalized with pneumonia and from age-frequency-matched controls were collected between August 2011 and August 2013. Swabs were tested for respiratory pathogens, including HRV, using quantitative real-time PCR assays. HRV-positive samples were sequenced for phylogenetic analysis by targeting the 5′ noncoding region (5′NCR). Our data showed that there were no differences in the prevalence of HRV detection among cases and controls (21% versus 20%, P = 0.693); however, among children 13 to 59 months old, HRV detection was more often case associated (21% versus 16%; P = 0.009), with the results mainly driven by HRV-C (12% versus 7%; P = 0.001). Overall, there were no differences in the results of molecular subtyping of the HRV species prevalence among cases (for HRV-A, 48%; for HRV-B, 7%; for HRV-C, 45%) and controls (for HRV-A, 45%; for HRV-B, 10%; for HRV-C, 45% [P = 0.496]). Those with pneumonia and HRV-C were older (12.1 versus 9.4 months, P = 0.033) and more likely to present with wheeze (35% versus 25%, P = 0.031) than those with HRV-A cases. Thus, the rate of HRV detection was high, with similar degrees of genetic diversity among cases and controls, confounding the interpretation of the presence of HRV in nasopharyngeal samples for attribution of a causal role in the pathogenesis of severe pneumonia in infants. However, among children 13 to 59 months of age, HRV detection, in particular, HRV-C detection, was associated with case status, especially among children with wheezing disease.

Cytokine Responses to Rhinovirus and Development of Asthma, Allergic Sensitization, and Respiratory Infections during Childhood

RATIONALE

Immunophenotypes of antiviral responses, and their relationship with asthma, allergy, and lower respiratory tract infections, are poorly understood.

OBJECTIVES

We characterized multiple cytokine responses of peripheral blood mononuclear cells to rhinovirus stimulation, and their relationship with clinical outcomes.

METHODS

In a population-based birth cohort, we measured 28 cytokines after stimulation with rhinovirus-16 in 307 children aged 11 years. We used machine learning to identify patterns of cytokine responses, and related these patterns to clinical outcomes, using longitudinal models. We also ascertained phytohemagglutinin-induced T-helper cell type 2 (Th2)-cytokine responses (PHA-Th2).

MEASUREMENTS AND MAIN RESULTS

We identified six clusters of children based on their rhinovirus-16 responses, which were differentiated by the expression of four cytokine/chemokine groups: interferon-related (IFN), proinflammatory (Inflam), Th2-chemokine (Th2-chem), and regulatory (Reg). Clusters differed in their clinical characteristics. Children with an IFN^modInflam^highestTh2-chem^highestReg^highest rhinovirus-16-induced pattern had a PHA-Th2^low response, and a very low asthma risk (odds ratio [OR], 0.08; 95% confidence interval [CI], 0.01-0.81; P = 0.03). Two clusters had a high risk of asthma and allergic sensitization, but with different trajectories from infancy to adolescence. The IFN^lowestInflam^highTh2-chem^lowReg^mod cluster exhibited a PHA-Th2^lowest response and was associated with early-onset asthma and sensitization, and the highest risk of asthma exacerbations (OR, 1.37; 95% CI, 1.07-1.76; P = 0.014) and lower respiratory tract infection hospitalizations (OR, 2.40; 95% CI, 1.26-4.58; P = 0.008) throughout childhood. In contrast, the IFN^highestInflam^modTh2-chem^modReg^high cluster with a rhinovirus-16-cytokine pattern was characterized by a PHA-Th2^highest response, and a low prevalence of asthma/sensitization in infancy that increased sharply to become the highest among all clusters by adolescence (but with a low risk of asthma exacerbations).

CONCLUSIONS

Early-onset troublesome asthma with early-life sensitization, later-onset milder allergic asthma, and disease protection are each associated with different patterns of rhinovirus-induced immune responses.

Respiratory Virus Epidemiology Among US Infants With Severe Bronchiolitis: Analysis of 2 Multicenter, Multiyear Cohort Studies

In 2 multicenter cohort studies of 2912 infants hospitalized for bronchiolitis during 2007-2014, the 5 most common pathogens were RSV (76.5%), rhinovirus (23.8%), coronavirus (6.9%), adenovirus (6.4%) and human metapneumovirus (6.0%). Hospitalization months significantly differed for these common pathogens (P ≤ 0.01), except for coronavirus (P = 0.30). There was a significant heterogeneity in temporal patterns by region in RSV-A and -B (both P < 0.001).

Genomic Circuitry Underlying Immunological Response to Pediatric Acute Respiratory Infection

Acute respiratory tract viral infections (ARTIs) cause significant morbidity and mortality. CD8 T cells are fundamental to host responses, but transcriptional alterations underlying anti-viral mechanisms and links to clinical characteristics remain unclear. CD8 T cell transcriptional circuitry in acutely ill pediatric patients with influenza-like illness was distinct for different viral pathogens. Although changes included expected upregulation of interferon-stimulated genes (ISGs), transcriptional downregulation was prominent upon exposure to innate immune signals in early IFV infection. Network analysis linked changes to severity of infection, asthma, sex, and age. An influenza pediatric signature (IPS) distinguished acute influenza from other ARTIs and outperformed other influenza prediction gene lists. The IPS allowed a deeper investigation of the connection between transcriptional alterations and clinical characteristics of acute illness, including age-based differences in circuits connecting the STAT1/2 pathway to ISGs. A CD8 T cell-focused systems immunology approach in pediatrics identified age-based alterations in ARTI host response pathways.

Lanosterol Synthase Regulates Human Rhinovirus Replication in Human Bronchial Epithelial Cells

Human rhinovirus (RV) infections are a significant risk factor for exacerbations of asthma and chronic obstructive pulmonary disease. Thus, approaches to prevent RV infection in such patients would give significant benefit. Through RNA interference library screening, we identified lanosterol synthase (LSS), a component of the cholesterol biosynthetic pathway, as a novel regulator of RV replication in primary normal human bronchial epithelial cells. Selective knock down of LSS mRNA with short interfering RNA inhibited RV2 replication in normal human bronchial epithelial cells. Small molecule inhibitors of LSS mimicked the effect of LSS mRNA knockdown in a concentration-dependent manner. We further demonstrated that the antiviral effect is not dependent on a reduction in total cellular cholesterol but requires a 24-hour preincubation with the LSS inhibitor. The rank order of antiviral potency of the LSS inhibitors used was consistent with LSS inhibition potency; however, all compounds showed remarkably higher potency against RV compared with the LSS enzyme potency. We showed that LSS inhibition led to an induction of 24(S),25 epoxycholesterol, an important regulator of the sterol pathway. We also demonstrated that LSS inhibition led to a profound increase in expression of the innate antiviral defense protein, IFN-β. We found LSS to be a novel regulator of RV replication and innate antiviral immunity and identified a potential molecular mechanism for this effect, via induction of 24(S),25 epoxycholesterol. Inhibition of LSS could therefore be a novel therapeutic target for prevention of RV-induced exacerbations.

Hijacking the Supplies: Metabolism as a Novel Facet of Virus-Host Interaction

Viral replication is a process that involves an extremely high turnover of cellular molecules. Since viruses depend on the host cell to obtain the macromolecules needed for their proper replication, they have evolved numerous strategies to shape cellular metabolism and the biosynthesis machinery of the host according to their specific needs. Technologies for the rigorous analysis of metabolic alterations in cells have recently become widely available and have greatly expanded our knowledge of these crucial host–pathogen interactions. We have learned that most viruses enhance specific anabolic pathways and are highly dependent on these alterations. Since uninfected cells are far more plastic in their metabolism, targeting of the virus-induced metabolic alterations is a promising strategy for specific antiviral therapy and has gained great interest recently. In this review, we summarize the current advances in our understanding of metabolic adaptations during viral infections, with a particular focus on the utilization of this information for therapeutic application.

Inflammasome activation is required for human rhinovirus-induced airway inflammation in naive and allergen-sensitized mice

Activation of the inflammasome is a key function of the innate immune response that regulates inflammation in response to microbial substances. Inflammasome activation by human rhinovirus (RV), a major cause of asthma exacerbations, has not been well studied. We examined whether RV induces inflammasome activation in vivo, molecular mechanisms underlying RV-stimulated inflammasome priming and activation, and the contribution of inflammasome activation to RV-induced airway inflammation and exacerbation. RV infection triggered lung mRNA and protein expression of pro-IL-1β and NLRP3, indicative of inflammasome priming, as well as cleavage of caspase-1 and pro-IL-1β, completing inflammasome activation. Immunofluorescence staining showed IL-1β in lung macrophages. Depletion with clodronate liposomes and adoptive transfer experiments showed macrophages to be required and sufficient for RV-induced inflammasome activation. TLR2 was required for RV-induced inflammasome priming in vivo. UV irradiation blocked inflammasome activation and RV genome was sufficient for inflammasome activation in primed cells. Naive and house dust mite-treated NLRP3-/- and IL-1β-/- mice, as well as IL-1 receptor antagonist-treated mice, showed attenuated airway inflammation and responsiveness following RV infection. We conclude that RV-induced inflammasome activation is required for maximal airway inflammation and hyperresponsiveness in naive and allergic mice. The inflammasome represents a molecular target for RV-induced asthma exacerbations.

Interleukin 1 Receptor-Like 1 (IL1RL1) Promotes Airway Bacterial and Viral Infection and Inflammation

Interleukin 1 receptor-like 1 (IL1RL1), also known as suppression of tumorigenicity 2 (ST2), is the receptor for interleukin 33 (IL-33) and has been increasingly studied in type 2 inflammation. An increase in airway IL-33/ST2 signaling in asthma has been associated with eosinophilic inflammation, but little is known about the role of ST2 in neutrophilic inflammation. Airway Mycoplasma pneumoniae and human rhinovirus (HRV) infections are linked to neutrophilic inflammation during acute exacerbations of asthma. However, whether ST2 contributes to M. pneumoniae- and HRV-mediated airway inflammation is poorly understood. The current study sought to determine the functions of ST2 during airway M. pneumoniae or HRV infection. In cultured normal human primary airway epithelial cells, ST2 overexpression (OE) increased the production of neutrophilic chemoattractant IL-8 in the absence or presence of M. pneumoniae or HRV1B infection. ST2 OE also enhanced HRV1B-induced IP-10, a chemokine involved in asthma exacerbations. In the M. pneumoniae-infected mouse model, ST2 deficiency, in contrast to sufficiency, significantly reduced the levels of neutrophils following acute (≤24 h) infection, while in the HRV1B-infected mouse model, ST2 deficiency significantly reduced the levels of proinflammatory cytokines KC, IP-10, and IL-33 in bronchoalveolar lavage (BAL) fluid. Overall, ST2 overexpression in human epithelial cells and ST2 sufficiency in mice increased the M. pneumoniae and HRV loads in cell supernatants and BAL fluid. After pathogen infection, ST2-deficient mice showed a higher level of the host defense protein lactotransferrin in BAL fluid. Our data suggest that ST2 promotes proinflammatory responses (e.g., neutrophils) to airway bacterial and viral infection and that blocking ST2 signaling may broadly attenuate airway infection and inflammation.