Persistence of rhinovirus RNA after asthma exacerbation in children

Biomarker defined infective and inflammatory asthma exacerbation phenotypes in hospitalized adults: clinical impact and phenotype stability at recurrent exacerbation

OBJECTIVE

Acute exacerbations (AEs) of asthma are heterogeneous in terms of triggers, outcomes, and treatment response. This study investigated biomarker defined infective and inflammatory AE phenotypes in hospitalized adult asthma patients, and their impact on clinical outcomes and phenotype stability at AE recurrence.

METHOD

Patients with asthma admitted with an AE between January 2010 and December 2011 with a 3-year follow-up were retrospectively studied. AEs were categorized into infective (CRP >10 mg/L) vs non-infective, eosinophilic (blood eosinophils ≥ 0.2 × 109 cells/L) vs non-eosinophilic, and viral (CRP >10 to <40 mg/L) vs bacterial (CRP ≥40 mg/L) phenotypes. Clinical impact of the index AE, the risk and time to a second AE and AE phenotype stability were analyzed using Kaplan-Meier survival curves and McNamar's test.

RESULT

294 asthma patients were included: 47% had infective AE with a longer length of stay than non-infective AE (2.0 vs. 1.0 days, p = 0.01). The proportion of patients with eosinophilic AEs was evenly distributed across infective and non-infective AE (40% vs. 46%), although more patients with viral had eosinophilia than bacterial AE (46% vs. 26%). During follow-up, 18% had recurrent AE; with a higher risk in viral AE than bacterial AE (25% vs. 8%, p = 0.02). Both inflammatory and infective AE phenotype were stable at recurrent AE.

CONCLUSION

AE phenotyping in hospitalized asthma patients, based on CRP and blood eosinophils, revealed prolonged hospital stay in infective AEs and a higher risk of recurrent AE requiring hospitalization in viral versus bacterial AEs. Moreover, infective, and inflammatory AE phenotypes were rather stable at recurrent AE. Our results suggest a role for biomarker guided phenotyping of AEs of asthma.

Do respiratory virus infections modify associations of asthma exacerbation with aeroallergens or fine particulate matter? A time series study in Philadelphia PA

Respiratory virus infections are related to over 80% of childhood asthma exacerbations. They enhance pro-inflammatory mediator release, especially for sensitized individuals exposed to pollens/molds. Using a time-series study design, we investigated possible effect modification by respiratory virus infections of the associations between aeroallergens/PM2.5 and asthma exacerbation rates. Outpatient, emergency department (ED), and inpatient visits for asthma exacerbation among children with asthma (28,540/24,444 [warm/cold season]), as well as viral infection counts were obtained from electronic health records of the Children's Hospital of Philadelphia from 2011 to 2016. Rate ratios (RRs, 90th percentile vs. 0) for late-season grass pollen were 1.00 (0.85-1.17), 1.04 (0.95-1.15), and 1.12 (0.96-1.32), respectively, for respiratory syncytial virus (RSV) counts within each tertile. However, similar trends were not observed for weed pollens/molds or PM2.5. Overall, our study provides little evidence supporting effect modification by respiratory viral infections.

Rhinovirus protease cleavage of nucleoporins: perspective on implications for airway remodeling

Human Rhinoviruses (RV) are a major cause of common colds and infections in early childhood and can lead to subsequent development of asthma via an as yet unknown mechanism. Asthma is a chronic inflammatory pulmonary disease characterized by significant airway remodeling. A key component of airway remodeling is the transdifferentiation of airway epithelial and fibroblast cells into cells with a more contractile phenotype. Interestingly, transforming growth factor-beta (TGF-β), a well characterized inducer of transdifferentiation, is significantly higher in airways of asthmatics compared to non-asthmatics. RV infection induces TGF-β signaling, at the same time nucleoporins (Nups), including Nup153, are cleaved by RV proteases disrupting nucleocytoplasmic transport. As Nup153 regulates nuclear export of SMAD2, a key intermediate in the TGF-β transdifferentiation pathway, its loss of function would result in nuclear retention of SMAD2 and dysregulated TGF-β signaling. We hypothesize that RV infection leads to increased nuclear SMAD2, resulting in sustained TGF-β induced gene expression, priming the airway for subsequent development of asthma. Our hypothesis brings together disparate studies on RV, asthma and Nup153 with the aim to prompt new research into the role of RV infection in development of asthma.

Rhinovirus induces airway remodeling: what are the physiological consequences?

BACKGROUND

Rhinovirus infections commonly evoke asthma exacerbations in children and adults. Recurrent asthma exacerbations are associated with injury-repair responses in the airways that collectively contribute to airway remodeling. The physiological consequences of airway remodeling can manifest as irreversible airway obstruction and diminished responsiveness to bronchodilators. Structural cells of the airway, including epithelial cells, smooth muscle, fibroblasts, myofibroblasts, and adjacent lung vascular endothelial cells represent an understudied and emerging source of cellular and extracellular soluble mediators and matrix components that contribute to airway remodeling in a rhinovirus-evoked inflammatory environment.

MAIN BODY

While mechanistic pathways associated with rhinovirus-induced airway remodeling are still not fully characterized, infected airway epithelial cells robustly produce type 2 cytokines and chemokines, as well as pro-angiogenic and fibroblast activating factors that act in a paracrine manner on neighboring airway cells to stimulate remodeling responses. Morphological transformation of structural cells in response to rhinovirus promotes remodeling phenotypes including induction of mucus hypersecretion, epithelial-to-mesenchymal transition, and fibroblast-to-myofibroblast transdifferentiation. Rhinovirus exposure elicits airway hyperresponsiveness contributing to irreversible airway obstruction. This obstruction can occur as a consequence of sub-epithelial thickening mediated by smooth muscle migration and myofibroblast activity, or through independent mechanisms mediated by modulation of the β2 agonist receptor activation and its responsiveness to bronchodilators. Differential cellular responses emerge in response to rhinovirus infection that predispose asthmatic individuals to persistent signatures of airway remodeling, including exaggerated type 2 inflammation, enhanced extracellular matrix deposition, and robust production of pro-angiogenic mediators.

CONCLUSIONS

Few therapies address symptoms of rhinovirus-induced airway remodeling, though understanding the contribution of structural cells to these processes may elucidate future translational targets to alleviate symptoms of rhinovirus-induced exacerbations.

Antibiotic use among admitted pediatric patients in the United States with status asthmaticus before and during the COVID-19 pandemic

OBJECTIVE

Hospital admission trends of children with status asthmaticus diminished during the Coronavirus-19 (COVID-19) pandemic of 2020, possibly secondary to several factors such as school closures and use of face masks. What effect this had on antibiotic prescribing practices has yet to be described. The objective of our study was to evaluate the use of antibiotics in hospitalized children with a diagnosis of status asthmaticus before and during the COVID pandemic.Methods: A retrospective cross-sectional analysis was conducted using the TriNetX® cloud-based program with a national and institutional database. Each database was queried for all inpatient pediatric encounters from 3 to 18 years old, admitted with a diagnosis of status asthmaticus in the spring seasons of 2017-2019. Admission data and antibiotic usage were queried during the COVID-19 pandemic year of 2020 from both databases and compared amongst all study years.Results: In 2020, there was an overall decrease in the number of admissions as compared to the average number from 2017-2019, by 76.9% in the national database (p < 0.05) and 91.2% in the institutional database. The rates of antibiotic prescriptions significantly dropped among the national database (p < 0.001, z = 3.39) and remained non-significantly changed among the institutional database (p = 0.944 and z = 0.073).Conclusions: Our study demonstrates that the COVID-19 pandemic year of 2020 coincided with a significant decrease in hospital admissions and antibiotic prescribing prevalence among children with status asthmaticus on a national level. Nonetheless, our reported trends in antibiotic prescribing are still grossly similar to that of pre-pandemic times and may demonstrate a continued need for antimicrobial stewardship.

Persistence of RNA Viruses in the Respiratory Tract: An Overview

Respiratory RNA viruses are a major cause of acute lower respiratory tract infections and contribute substantially to hospitalization among infants, elderly, and immunocompromised. Complete viral clearance from acute infections is not always achieved, leading to persistence. Certain chronic respiratory diseases like asthma and chronic obstructive pulmonary disease have been associated with persistent infection by human respiratory syncytial virus and human rhinovirus, but it is still not clear whether RNA viruses really establish long-term infections as it has been recognized for DNA viruses as human bocavirus and adenoviruses. Herein, we summarize evidence of RNA virus persistence in the human respiratory tract, as well as in some animal models, to highlight how long-term infections might be related to development and/or maintenance of chronic respiratory symptoms.

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

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

Why does viral RNA sometimes persist after recovery from acute infections?

DNA viruses often persist in the body of their host, becoming latent and recurring many months or years later. By contrast, most RNA viruses cause acute infections that are cleared from the host as they lack the mechanisms to persist. However, it is becoming clear that viral RNA can persist after clinical recovery and elimination of detectable infectious virus. This persistence can either be asymptomatic or associated with late progressive disease or nonspecific lingering symptoms, such as may be the case following infection with Ebola or Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Why does viral RNA sometimes persist after recovery from an acute infection? Where does the RNA come from? And what are the consequences?

Nasal interferon responses to community rhinovirus infections are similar in controls and children with asthma

BACKGROUND

Rhinovirus (RV) is the main cause of asthma exacerbations in children. Some studies reported that persons with asthma have attenuated interferon (IFN) responses to experimental RV infection compared with healthy individuals. However, responses to community-acquired RV infections in controls and children with asthma have not been compared.

OBJECTIVE

To evaluate nasal cytokine responses after natural RV infections in people with asthma and healthy children.

METHODS

We compared nasal cytokine expression among controls and children with asthma during healthy, virus-negative surveillance weeks and self-reported RV-positive sick weeks. A total of 14 controls and 21 patients with asthma were studied. Asthma disease severity was based on symptoms and medication use. Viral genome was detected by multiplex polymerase chain reaction. Nasal cytokine protein levels were determined by multiplex assays.

RESULTS

Two out of 47 surveillance weeks tested positive for RV, illustrating an asymptomatic infection rate of 5%. A total of 38 of 47 sick weeks (81%) tested positive for the respiratory virus. Of these, 33 (87%) were positive for RV. During well weeks, nasal interleukin 8 (IL-8), IL-12, and IL-1β levels were higher in children with asthma than controls. Compared with healthy virus-negative surveillance weeks, IL-8, IL-13, and interferon beta increased during colds only in patients with asthma. In both controls and children with asthma, the nasal levels of interferon gamma, interferon lambda-1, IL-1β, IL-8, and IL-10 increased during RV-positive sick weeks. During RV infection, IL-8, IL-1β, and tumor necrosis factor-α levels were strongly correlated.

CONCLUSION

In both controls and patients with asthma, natural RV infection results in robust type II and III IFN responses.

A bird eye view on cystic fibrosis: An underestimated multifaceted chronic disorder

Cystic fibrosis (CF) is an autosomal recessive disease which involves the mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. CF involves in the inflammatory processes and is considered as a multisystem disorder that is not confined to lungs, but it also affects other vital organs that leads to numerous co-morbidities. The respiratory disorder in the CF results in mortality and morbidity which is characterized by series of serious events involving mucus hypersecretion, microbial infections, airways obstruction, inflammation, destruction of epithelium, tissue remodeling and terminal lung diseases. Mucins are the high molecular weight glycoproteins important for the viscoelastic properties of the mucus, play a significant role in the disease mechanisms. Determining the functional association between the CFTR and mucins might help to identify the putative target for specific therapeutic approach. In fact, furin enzyme which helps in the entry of novel COVID-19 virus into the cell, is upregulated in CF and this can also serve as a potential target for CF treatment. Moreover, the use of nano-formulations for CF treatment is an area of research being widely studied as they have also demonstrated promising outcomes. The in-depth knowledge of non-coding RNAs like miRNAs and lncRNAs and their functional association with CFTR gene expression and mutation can provide a different range of opportunity to identify the promising therapeutic approaches for CF.

Host Antiviral Response Suppresses Ciliogenesis and Motile Ciliary Functions in the Nasal Epithelium

Background

Respiratory viral infections are one of the main drivers of development and exacerbation for chronic airway inflammatory diseases. Increased viral susceptibility and impaired mucociliary clearance are often associated with chronic airway inflammatory diseases and served as risk factors of exacerbations. However, the links between viral susceptibility, viral clearance, and impaired mucociliary functions are unclear. Therefore, the objective of this study is to provide the insights into the effects of improper clearance of respiratory viruses from the epithelium following infection, and their resulting persistent activation of antiviral response, on mucociliary functions.

Methods

In order to investigate the effects of persistent antiviral responses triggered by viral components from improper clearance on cilia formation and function, we established an in vitro air–liquid interface (ALI) culture of human nasal epithelial cells (hNECs) and used Poly(I:C) as a surrogate of viral components to simulate their effects toward re-epithelization and mucociliary functions of the nasal epithelium following damages from a viral infection.

Results

Through previous and current viral infection expression data, we found that respiratory viral infection of hNECs downregulated motile cilia gene expression. We then further tested the effects of antiviral response activation on the differentiation of hNECs using Poly(I:C) stimulation on differentiating human nasal epithelial stem/progenitor cells (hNESPCs). Using this model, we observed reduced ciliated cell differentiation compared to goblet cells, reduced protein and mRNA in ciliogenesis-associated markers, and increased mis-assembly and mis-localization of ciliary protein DNAH5 following treatment with 25 μg/ml Poly(I:C) in differentiating hNECs. Additionally, the cilia length and ciliary beat frequency (CBF) were also decreased, which suggest impairment of ciliary function as well.

Conclusion

Our results suggest that the impairments of ciliogenesis and ciliary function in hNECs may be triggered by specific expression of host antiviral response genes during re-epithelization of the nasal epithelium following viral infection. This event may in turn drive the development and exacerbation of chronic airway inflammatory diseases.

High burden of viral respiratory co-infections in a cohort of children with suspected pulmonary tuberculosis

Background

The presentation of pulmonary tuberculosis (PTB) in young children is often clinically indistinguishable from other common respiratory illnesses, which are frequently infections of viral aetiology. As little is known about the role of viruses in children with PTB, we investigated the prevalence of respiratory viruses in children with suspected PTB at presentation and follow-up.

Methods

In an observational cohort study, children < 13 years were routinely investigated for suspected PTB in Cape Town, South Africa between December 2015 and September 2017 and followed up for 24 weeks. Nasopharyngeal aspirates (NPAs) were tested for respiratory viruses using multiplex PCR at enrolment, week 4 and 8.

Results

Seventy-three children were enrolled [median age 22.0 months; (interquartile range 10.0–48.0); 56.2% male and 17.8% HIV-infected. Anti-tuberculosis treatment was initiated in 54.8%; of these 50.0% had bacteriologically confirmed TB. At enrolment, ≥1 virus were detected in 95.9% (70/73) children; most commonly human rhinovirus (HRV) (74.0%). HRV was more frequently detected in TB cases (85%) compared to ill controls (60.6%) (p = 0.02). Multiple viruses were detected in 71.2% of all children; 80% of TB cases and 60.6% of ill controls (p = 0.07). At follow-up, ≥1 respiratory virus was detected in 92.2% (47/51) at week 4, and 94.2% (49/52) at week 8.

Conclusions

We found a high prevalence of viral respiratory co-infections in children investigated for PTB, irrespective of final PTB diagnosis, which remained high during follow up. Future work should include investigating the whole respiratory ecosystem in combination with pathogen- specific immune responses.

Detection of Respiratory Syncytial Virus or Rhinovirus Weeks After Hospitalization for Bronchiolitis and the Risk of Recurrent Wheezing

BACKGROUND

In severe bronchiolitis, it is unclear if delayed clearance or sequential infection of respiratory syncytial virus (RSV) or rhinovirus (RV) is associated with recurrent wheezing.

METHODS

In a 17-center severe bronchiolitis cohort, we tested nasopharyngeal aspirates (NPA) upon hospitalization and 3 weeks later (clearance swab) for respiratory viruses using PCR. The same RSV subtype or RV genotype in NPA and clearance swab defined delayed clearance (DC); a new RSV subtype or RV genotype at clearance defined sequential infection (SI). Recurrent wheezing by age 3 years was defined per national asthma guidelines.

RESULTS

Among 673 infants, RSV DC and RV DC were not associated with recurrent wheezing, and RSV SI was rare. The 128 infants with RV SI (19%) had nonsignificantly higher risk of recurrent wheezing (hazard ratio [HR], 1.31; 95% confidence interval [CI], .95-1.80; P = .10) versus infants without RV SI. Among infants with RV at hospitalization, those with RV SI had a higher risk of recurrent wheezing compared to children without RV SI (HR, 2.49; 95% CI, 1.22-5.06; P = .01).

CONCLUSIONS

Among infants with severe bronchiolitis, those with RV at hospitalization followed by a new RV infection had the highest risk of recurrent wheezing.

Respiratory Viral Infections in Exacerbation of Chronic Airway Inflammatory Diseases: Novel Mechanisms and Insights From the Upper Airway Epithelium

Respiratory virus infection is one of the major sources of exacerbation of chronic airway inflammatory diseases. These exacerbations are associated with high morbidity and even mortality worldwide. The current understanding on viral-induced exacerbations is that viral infection increases airway inflammation which aggravates disease symptoms. Recent advances in in vitro air-liquid interface 3D cultures, organoid cultures and the use of novel human and animal challenge models have evoked new understandings as to the mechanisms of viral exacerbations. In this review, we will focus on recent novel findings that elucidate how respiratory viral infections alter the epithelial barrier in the airways, the upper airway microbial environment, epigenetic modifications including miRNA modulation, and other changes in immune responses throughout the upper and lower airways. First, we reviewed the prevalence of different respiratory viral infections in causing exacerbations in chronic airway inflammatory diseases. Subsequently we also summarized how recent models have expanded our appreciation of the mechanisms of viral-induced exacerbations. Further we highlighted the importance of the virome within the airway microbiome environment and its impact on subsequent bacterial infection. This review consolidates the understanding of viral induced exacerbation in chronic airway inflammatory diseases and indicates pathways that may be targeted for more effective management of chronic inflammatory diseases.

An investigation into respiratory tract viruses in children with acute lower respiratory tract infection or wheezing

BACKGROUND

This study aimed to determine the frequencies of respiratory tract viruses in patient (acute lower respiratory tract infection [LRTI] or wheezing) and control (history of asthma without symptoms) groups.

METHODS

Using multiplex-polymerase chain reaction (PCR), respiratory tract viruses were investigated in the respiratory tract specimens from patient and control groups followed in the Pediatric Clinic.

RESULTS

The viruses detected in the patient and control groups (P=0.013) were as follows, respectively: rhinoviruses A, B, C (25.6% and 36.7%), influenza virus A (21.1% and 0.0%), parainfluenza virus type 1 (7.8% and 1.7%), parainfluenza virus type 4 (5.6% and 0.0%), adenoviruses A, B, C, D, E (4.4% and 1.7%), parainfluenza virus type 3 (4.4% and 1.7%), coronaviruses 229E and NL63 (4.4% and 1.7%), coronavirus OC43 (3.3% and 0.0%), respiratory syncytial virus A (3.3% and 0.0%), parainfluenza virus type 2 (2.2% and 0.0%), influenza virus B (2.2% and 0.0%), and respiratory syncytial virus B (1.1% and 1.7%). No bocavirus, metapneumovirus or enterovirus was found in any specimen. Statistically significant differences in the detection of influenza virus A (P=0.000), the total detection of parainfluenza viruses (P=0.008) and coinfection (P=0.004) were observed between the patient and control groups.

CONCLUSIONS

The advantage of our study compared with other studies is the inclusion of not only wheezing patients but also children with asthma without symptom. The higher detection of rhinoviruses both in patient and control groups give rise to thought that these viruses may be responsible for asthma exacerbations and may be related with long duration of virus shedding.

Respiratory pathogens and clinical outcomes in children with an asthma exacerbation: A systematic review

BACKGROUND

In asthmatic children, respiratory pathogens are identified in 60%-80% of asthma exacerbations, contributing to a significant burden of illness. The role of pathogens in the clinical evolution of exacerbations is unknown.

OBJECTIVE

We systematically reviewed the association between the presence of pathogens and clinical outcomes in children with an asthma exacerbation.

METHOD

PubMed, EMBASE, BIOSIS, and the Cochrane Central Register of Controlled Trials were searched up to October 2016 for studies reporting on respiratory pathogen exposure and clinical outcome. The Risk of Bias in Non-Randomized Studies of Interventions tool was used for quality assessment.

RESULTS

Twenty-eight observational studies (N = 4,224 children) reported on 112 different associations between exposure to any pathogen (n = 45), human rhinovirus (HRV; n = 34), atypical bacteria (n = 21), specific virus (n = 11), or bacteria (n = 1) and outcomes of exacerbation severity (n = 26), health care use (n = 38), treatment response (n = 19), and morbidity (n = 29). Restricting the analysis only to comparisons with a low to moderate risk of bias, we observed an association between HRV and higher exacerbation severity on presentation (regression p = .016) and between the presence of any pathogen and emergency department treatment failure (odds ratio [OR] = 1.57; 95% CI 1.04% to 2.37%). High-quality evidence for effect on morbidity or health care use is lacking.

CONCLUSIONS

Further research on the role of pathogen-treatment interaction and outcomes is required to inform the need for point-of-care, real-time testing for pathogens. Studies with a sufficiently large sample size that address selection bias, correctly adjust for confounding, and rigorously report core patient-centred outcomes are necessary to improve knowledge.

Nasal IgE production in allergic rhinitis: Impact of rhinovirus infection

BACKGROUND

Rhinovirus (RV) infections exacerbate asthma in part by enhancing an allergic state, and these exacerbations can be mitigated via administration of anti-IgE.

OBJECTIVE

We investigated the presence of local IgE production in the nose of allergic and non-allergic subjects and assessed whether this was enhanced by RV.

METHODS

Local production of specific IgE was determined by comparing ratios of specific to total IgE concentrations between nasal and serum samples. Our initial studies were performed in subjects presenting to the emergency department for allergic and non-allergic respiratory complaints. Subsequently, we investigated influences of experimental RV infection on nasal sIgE production in an allergic cohort.

RESULTS

We found evidence of local sIgE production to Dermatophagoides pteronyssinus in 30.3% and to Blomia tropicalis in 14.6% of allergic subjects. None of the non-allergic subjects demonstrated local IgE. Subjects with active RV infection were more than twice as likely to have local sIgE (45% vs 14%), and subjects with local sIgE being produced were ~3 times more likely to be having an asthma exacerbation. Experimental RV infection was able to induce local sIgE production.

CONCLUSION

These studies confirm local IgE production in a large subset of allergic subjects and demonstrate that allergic asthmatics with local IgE are more likely to develop an asthma exacerbation when infected with RV. Our RV challenge studies demonstrate that at least some allergic asthmatics can be induced to secrete locally generated IgE in their nasal airway after RV infection.

Emerging Regulatory Roles of Dual-Specificity Phosphatases in Inflammatory Airway Disease

Inflammatory airway disease, such as asthma and chronic obstructive pulmonary disease (COPD), is a major health burden worldwide. These diseases cause large numbers of deaths each year due to airway obstruction, which is exacerbated by respiratory viral infection. The inflammatory response in the airway is mediated in part through the MAPK pathways: p38, JNK and ERK. These pathways also have roles in interferon production, viral replication, mucus production, and T cell responses, all of which are important processes in inflammatory airway disease. Dual-specificity phosphatases (DUSPs) are known to regulate the MAPKs, and roles for this family of proteins in the pathogenesis of airway disease are emerging. This review summarizes the function of DUSPs in regulation of cytokine expression, mucin production, and viral replication in the airway. The central role of DUSPs in T cell responses, including T cell activation, differentiation, and proliferation, will also be highlighted. In addition, the importance of this protein family in the lung, and the necessity of further investigation into their roles in airway disease, will be discussed.

PCR Detection of Respiratory Pathogens in Asymptomatic and Symptomatic Adults

The frequency of viral respiratory pathogens in asymptomatic subjects is poorly defined. The aim of this study was to explore the prevalence of respiratory pathogens in the upper airways of asymptomatic adults, compared with a reference population of symptomatic patients sampled in the same centers during the same period. Nasopharyngeal (NP) swab samples were prospectively collected from adults with and without ongoing symptoms of respiratory tract infection (RTI) during 12 consecutive months, in primary care centers and hospital emergency departments, and analyzed for respiratory pathogens by a PCR panel detecting 16 viruses and four bacteria. Altogether, 444 asymptomatic and 75 symptomatic subjects completed sampling and follow-up (FU) at day 7. In the asymptomatic subjects, the detection rate of viruses was low (4.3%), and the most common virus detected was rhinovirus (3.2%). Streptococcus pneumoniae was found in 5.6% of the asymptomatic subjects and Haemophilus influenzae in 1.4%. The only factor independently associated with low viral detection rate in asymptomatic subjects was age ≥65 years (P = 0.04). An increased detection rate of bacteria was seen in asymptomatic subjects who were currently smoking (P < 0.01) and who had any chronic condition (P < 0.01). We conclude that detection of respiratory viruses in asymptomatic adults is uncommon, suggesting that a positive PCR result from a symptomatic patient likely is relevant for ongoing respiratory symptoms. Age influences the likelihood of virus detection among asymptomatic adults, and smoking and comorbidities may increase the prevalence of bacterial pathogens in the upper airways.

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.

The human viral challenge model: accelerating the evaluation of respiratory antivirals, vaccines and novel diagnostics

The Human Viral Challenge (HVC) model has, for many decades, helped in the understanding of respiratory viruses and their role in disease pathogenesis. In a controlled setting using small numbers of volunteers removed from community exposure to other infections, this experimental model enables proof of concept work to be undertaken on novel therapeutics, including vaccines, immunomodulators and antivirals, as well as new diagnostics.Crucially, unlike conventional phase 1 studies, challenge studies include evaluable efficacy endpoints that then guide decisions on how to optimise subsequent field studies, as recommended by the FDA and thus licensing studies that follow. Such a strategy optimises the benefit of the studies and identifies possible threats early on, minimising the risk to subsequent volunteers but also maximising the benefit of scarce resources available to the research group investing in the research. Inspired by the principles of the 3Rs (Replacement, Reduction and Refinement) now commonly applied in the preclinical phase, HVC studies allow refinement and reduction of the subsequent development phase, accelerating progress towards further statistically powered phase 2b studies. The breadth of data generated from challenge studies allows for exploration of a wide range of variables and endpoints that can then be taken through to pivotal phase 3 studies.We describe the disease burden for acute respiratory viral infections for which current conventional development strategies have failed to produce therapeutics that meet clinical need. The Authors describe the HVC model's utility in increasing scientific understanding and in progressing promising therapeutics through development.The contribution of the model to the elucidation of the virus-host interaction, both regarding viral pathogenicity and the body's immunological response is discussed, along with its utility to assist in the development of novel diagnostics.Future applications of the model are also explored.

IFNΛ3/4 locus polymorphisms and IFNΛ3 circulating levels are associated with COPD severity and outcomes

BACKGROUND

Interferon lambdas (IFNLs) have important anti-viral/bacterial and immunomodulatory functions in the respiratory tract. How do IFNLs impact COPD and its exacerbations?

METHODS

Five hundred twenty eight patients were recruited in a prospective observational multicentre cohort (PROMISE) study. The genetic polymorphisms (rs8099917 and rs12979860) within the IFNL3/4 gene region and circulating levels of IFNL3 in COPD patients were determined and associated with disease activity and outcome during a median follow-up of 24 months.

RESULTS

The GG genotype significantly influenced severe exacerbation rate (42 vs. 23%; p = 0.032) and time to severe exacerbation (HR = 2.260; p = 0.012). Compared to the TT or TG genotypes, the GG genotype was associated with severe dyspnoea (modified medical research council score ≥ median 3; 22 vs 42%, p = 0.030). The CC genotype of the rs12979860 SNP was associated with a poorer prognosis (body mass index, airflow obstruction, dyspnea and exercise capacity index ≥ median 4; 46 vs. 36% TC vs. 20.5% TT; p = 0.031). Patients with stable COPD and at exacerbation had significantly lower circulating IFNL3 compared to healthy controls (p < 0.001 and p < 0.001, respectively). Circulating IFNL3 correlated to post-bronchodilator FEV1%predicted and the tissue maturation biomarker Pro-collagen 3.

CONCLUSION

IFNL3/4 polymorphisms and circulating IFNL3 may be associated with disease activity and outcomes in COPD.

TRIAL REGISTRATION

Clinical Trial registration http://www.isrctn.com/ identifier ISRCTN99586989 on 16 April 2008.

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.

Immune Responses in Rhinovirus-Induced Asthma Exacerbations

Acute asthma exacerbations are responsible for urgent care visits and hospitalizations; they interfere with school and work productivity, thereby driving much of the morbidity and mortality associated with asthma. Approximately 80 to 85 % of asthma exacerbations in children, adolescents, and less frequently adults are associated with viral upper respiratory tract viral infections, and rhinovirus (RV) accounts for ∼60-70 % of these virus-associated exacerbations. Evidence suggests that it is not the virus itself but the nature of the immune response to RV that drives this untoward response. In particular, evidence supports the concept that RV acts to exacerbate an ongoing allergic inflammatory response to environmental allergens present at the time of the infection. The interaction of the ongoing IgE- and T cell-mediated response to allergen superimposed on the innate and adaptive immune responses to the virus and how this leads to triggering of an asthma exacerbation is discussed.

A Tool for Investigating Asthma and COPD Exacerbations: A Newly Manufactured and Well Characterised GMP Wild-Type Human Rhinovirus for Use in the Human Viral Challenge Model

Background

Human Rhinovirus infection is an important precursor to asthma and chronic obstructive pulmonary disease exacerbations and the Human Viral Challenge model may provide a powerful tool in studying these and other chronic respiratory diseases. In this study we have reported the production and human characterisation of a new Wild-Type HRV-16 challenge virus produced specifically for this purpose.

Methods and Stock Development

A HRV-16 isolate from an 18 year old experimentally infected healthy female volunteer (University of Virginia Children’s Hospital, USA) was obtained with appropriate medical history and consent. We manufactured a new HRV-16 stock by minimal passage in a WI-38 cell line under Good Manufacturing Practice conditions. Having first subjected the stock to rigorous adventitious agent testing and determining the virus suitability for human use, we conducted an initial safety and pathogenicity clinical study in adult volunteers in our dedicated clinical quarantine facility in London.

Human Challenge and Conclusions

In this study we have demonstrated the new Wild-Type HRV-16 Challenge Virus to be both safe and pathogenic, causing an appropriate level of disease in experimentally inoculated healthy adult volunteers. Furthermore, by inoculating volunteers with a range of different inoculum titres, we have established the minimum inoculum titre required to achieve reproducible disease. We have demonstrated that although inoculation titres as low as 1 TCID₅₀ can produce relatively high infection rates, the optimal titre for progression with future HRV challenge model development with this virus stock was 10 TCID₅₀. Studies currently underway are evaluating the use of this virus as a challenge agent in asthmatics.

Trial Registration

ClinicalTrials.gov NCT02522832

Rhinovirus and childhood asthma: an update

Asthma is recognized as a complex disease resulting from interactions between multiple genetic and environmental factors. Accumulating evidence suggests that respiratory viral infections in early life constitute a major environmental risk factor for the development of childhood asthma. Respiratory viral infections have also been recognized as the most common cause of asthma exacerbation. The advent of molecular diagnostics to detect respiratory viruses has provided new insights into the role of human rhinovirus (HRV) infections in the pathogenesis of asthma. However, it is still unclear whether HRV infections cause asthma or if wheezing with HRV infection is simply a predictor of childhood asthma. Recent clinical and experimental studies have identified plausible pathways by which HRV infection could cause asthma, particularly in a susceptible host, and exacerbate disease. Airway epithelial cells, the primary site of infection and replication of HRV, play a key role in these processes. Details regarding the role of genetic factors, including ORMDL3, are beginning to emerge. This review discusses recent clinical and experimental evidence for the role of HRV infection in the development and exacerbation of childhood asthma and the potential underlying mechanisms that have been proposed.

Influenza Virus Detection Following Administration of Live-Attenuated Intranasal Influenza Vaccine in Children With Cystic Fibrosis and Their Healthy Siblings

Background.  We aimed to explore the detection profile of influenza viruses following live-attenuated intranasal influenza vaccination (LAIV) in children aged 2-19 years with and without cystic fibrosis (CF). Methods.  Before the 2013-2014 influenza season, flocked nasal swabs were obtained before vaccination and 4 times in the week of follow-up from 76 participants (n_CF: 57; n_healthy: 19). Influenza was detected by reverse transcription polymerase chain reaction (RT-PCR) assays. A Bayesian hierarchical logistic regression model was used to estimate the effect of CF status and age on influenza detection. Results.  Overall, 69% of the study cohort shed influenza RNA during follow-up. The mean duration of RT-PCR detection was 2.09 days (95% credible interval [CrI]: 1.73-2.48). The odds of influenza RNA detection on day 1 following vaccination decreased with age in years (odds ratio [OR]: 0.82 per year; 95% CrI: 0.70-0.95), and subjects with CF had higher odds of influenza RNA detection on day 1 of follow-up (OR: 5.09; 95% CrI: 1.02-29.9). Conclusion.  Despite the small sample size, our results indicate that LAIV vaccine strains are detectable during the week after LAIV, mainly in younger individuals and vaccinees with CF. It remains unclear whether recommendations for avoiding contact with severely immunocompromised patients should differ for these groups.

Presence of rhinovirus in the respiratory tract of adolescents and young adults with asthma without symptoms of infection

Background

Viral respiratory infections have been associated with up to 80% of wheezing episodes and asthma exacerbations. However, studies on the role of these viruses in asthmatic patients in the interval between exacerbations are sparse. This study aimed to determine the presence of respiratory viruses, without symptoms of infection, in the airways of young asthmatics as compared to healthy controls.

Material and Methods

Patients 10–35 years of age with stable asthma and a group of healthy controls were analyzed regarding the presence of RNA from common respiratory viruses in nasopharyngeal aspirates by PCR. Self-reported asthma control and quality of life, fraction of exhaled nitric oxide (FeNO), spirometry, and bronchial responsiveness to methacholine were recorded. Blood samples were collected to assess IgE sensitisation and eosinophil cationic protein (ECP) levels.

Results

In 354 patients with asthma and 108 healthy controls, human rhinovirus (HRV) was the only virus detected (4.5% of asthmatics vs. 0.9% of controls; p = 0.08). HRV⁺ asthma patients had a higher degree of aeroallergen IgE sensitisation (median 37.7 vs. 10.4 kU_A/L, p = 0.04), and a tendency for higher levels of serum ECP (median 17.2 vs. 12.6 μg/L, p = 0.07), as compared to their HRV⁻ counterparts.

Conclusions

Absence of symptoms of respiratory tract infection notwithstanding, HRV seems to be more prevalent in the airways of adolescents and young adults with asthma and a high degree of aeroallergen IgE sensitisation than in controls. The presence of HRV seems also to be related to systemic eosinophilic inflammation despite ongoing treatment with inhaled corticosteroids.

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Cross-sectional study on adolescents and young adults with asthma and healthy controls.

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Common respiratory viruses examined in nasopharyngeal aspirates by PCR.

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Only rhinovirus detected in subjects without symptoms of respiratory tract infection.

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Prevalence of rhinovirus tended to be higher in asthmatics compared to controls.

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Presence of rhinovirus associated with high degree of aeroallergen IgE sensitisation.

Risk factors for acute asthma in tropical America: a case-control study in the City of Esmeraldas, Ecuador

BACKGROUND

Despite the high asthma rates described in Latin America, asthma risk factors in poor urban settings are not well established. We investigated risk factors for acute asthma among Ecuadorian children.

METHODS

A matched case-control study was carried out in a public hospital serving a coastal city. Children with acute asthma were age- and sex-matched to non-asthmatics. A questionnaire was administered, and blood, as well as stool, and nasopharyngeal swabs were collected.

RESULTS

Sixty cases and 119 controls aged 5-15 were evaluated. High proportions of cases were atopic with population-attributable fractions for atopy of 68.5% for sIgE and 57.2% for SPT. Acute asthma risk increased with greater titers of mite IgE (3.51-50 kU/l vs. <0.70kU/l - OR 4.56, 95% CI 1.48-14.06, p = 0.008; >50kU/l vs. <0.70kU/l - OR 41.98, 95% CI: 8.97-196.39, p < 0.001). Asthma risk was significantly independently associated with bronchiolitis (adj. OR: 38.9, 95% CI 3.26-465), parental educational level (adj. OR 1.26, 95% CI: 1.08-1.46), and presence of sIgE (adj. OR: 36.7, 95% CI: 4.00-337), while a reduced risk was associated with current contact with pets (adj. OR: 0.07, 95% CI: 0.01-0.56). Rhinovirus infection was more frequent in cases (cases 35.6% vs. controls 7.8%, p = 0.002). None of the cases were on maintenance therapy with inhaled corticosteroids and most relied on emergency department for control.

CONCLUSIONS

A high proportion of children presenting to a public hospital with acute asthma were allergic to mite, particularly at high IgE titer. Poor asthma control resulted in overuse of emergency care.

Response of airway epithelial cells to double-stranded RNA in an allergic environment

Background

Respiratory viral infections are the most common trigger of acute exacerbations in patients with allergic asthma. The anti-viral response of airway epithelial cells (AEC) may be impaired in asthmatics, while cytokines produced by AEC may drive the inflammatory response. We investigated whether AEC cultured in the presence of Th2 cytokines associated with an allergic environment exhibited altered responses to double-stranded RNA, a virus-like stimulus.

Methods

We undertook preliminary studies using the MLE-12 cell line derived from mouse distal respiratory epithelial cells, then confirmed and extended our findings using low-passage human AEC. Cells were cultured in the absence or presence of the Th2 cytokines IL-4 and IL-13 for 48 hours, then stimulated with poly I:C for 4 hours. Expression of relevant anti-viral response and cytokine genes was assessed by quantitative real-time PCR. Secretion of cytokine proteins was assessed by immunoassay.

Results

Following stimulation with poly I:C, MLE-12 cells pre-treated with Th2 cytokines exhibited significantly higher levels of expression of mRNA for the cytokine genes Cxcl10 and Cxcl11, as well as a trend towards increased expression of Cxcl9 and Il6. Expression of anti-viral response genes was mostly unchanged, although Stat1, Ifit1 and Ifitm3 were significantly increased in Th2 cytokine pre-treated cells. Human AEC pre-treated with IL-4 and IL-13, then stimulated with poly I:C, similarly exhibited significantly higher expression of IL8, CXCL9, CXCL10, CXCL11 and CCL5 genes. In parallel, there was significantly increased secretion of CXCL8 and CCL5, as well as a trend towards increased secretion of CXCL10 and IL-6. Again, expression of anti-viral response genes was not decreased. Rather, there was significantly enhanced expression of mRNA for type III interferons, RNA helicases and other interferon-stimulated genes.

Conclusion

The Th2 cytokine environment appears to promote increased production of pro-inflammatory chemokines by AEC in response to double-stranded RNA, which could help explain the exaggerated inflammatory response to respiratory viral infection in allergic asthmatics. However, any impairment of anti-viral host defences in asthmatics appears unlikely to be a consequence of Th2 cytokine-induced downregulation of the expression of viral response genes by AEC.

Electronic supplementary material

The online version of this article (doi:10.1186/s40247-014-0011-6) contains supplementary material, which is available to authorized users.

Rhinovirus and the developing lung

Human rhinovirus (HRV) infections are now widely accepted as the commonest cause of acute respiratory illnesses (ARIs) in children. Advanced PCR techniques have enabled HRV infections to be identified as causative agents in most common ARIs in childhood including bronchiolitis, acute asthma, pneumonia and croup. However, the long-term implications of rhinovirus infections are less clear. The aim of this review is to examine the relationship between rhinovirus infections and disorders of the lower airways in childhood.

Chronic rhinovirus infection in an adult with cystic fibrosis

Rhinovirus is a common cause of exacerbations of cystic fibrosis (CF) and is usually considered a self-limiting infection. We report a case of chronic infection with rhinovirus A type 33 in a 43-year-old male with CF which has persisted for over 2 years.

Human rhinovirus and wheezing: short and long-term associations in children

OBJECTIVES

Human rhinoviruses (HRVs) have been suggested to play a role in the development of childhood wheezing. However, whether HRV is causally related to the development of wheezing or HRV-associated wheeze is merely an indicator of disease susceptibility is unclear. Our aim was to study the role of HRV during infancy in the development of lower respiratory disease during infancy and childhood.

METHODS

In a population-based birth cohort, during the 1st year of life, nose and throat swabs were collected on a monthly basis, regardless of any symptoms. Polymerase chain reaction was used to detect an extensive panel of respiratory pathogens. Lung function was measured before 2 months of age. Information on respiratory symptoms was collected by daily questionnaires and electronic patient files.

RESULTS

1425 samples were collected in 140 infants. Both the presence of (single or multiple) pathogens (HRV equal to other pathogens) and increased respiratory system resistance were significantly associated with lower respiratory symptoms during infancy. HRV presence during infancy was not associated with the risk of wheezing at age 4, but every HRV episode with wheezing increased the risk of wheezing at age 4 (odds ratio 1.9, 1.1-3.5). This association weakened after adjustment for lung function (odds ratio 1.4, 0.7-2.9).

CONCLUSIONS

HRV and other viruses are associated with lower respiratory symptoms during infancy, as well as a high presymptomatic respiratory system resistance. HRV presence during infancy is not associated with childhood wheezing, but wheeze during a HRV episode is an indicator of children at high risk for childhood wheeze, partly because of a reduced neonatal lung function.

Virus infections among young children--the first year of the INDIS study

The frequencies of early childhood infections were studied in healthy children with increased genetic risk for type 1 diabetes participating in the ongoing prospective high intensive infection follow-up Study, INDIS, started in 2009 in Turku, Finland. Here the results obtained from 160 stool to 160 nasal swab specimens collected in parallel at times of infectious symptoms in 2009-2010 from 45 children at the age of 24 months or younger are reported. The specimens were analyzed for enteric (human enterovirus, norovirus, rotavirus, sapovirus, astrovirus) and respiratory RNA viruses (human enterovirus and rhinovirus) common in early childhood, respectively, using highly validated virus-specific real-time PCR methods. According to the results 96% of the children had at least one virus infection during the study period and one or several viral agents were detected in 76% of sample sets. The most prevalent viral agents were human rhinovirus, enterovirus, parechovirus, and norovirus (genotype GII) with positive specimens 57.5%, 28.8%, 19.4%, and 6.9%, respectively. Other intestinal viruses were found in less than 2% of stool specimens. Single infections covered 40.0% of the specimens while multiple infections with two or more infectious agents were detected in 36.3% of specimens and altogether 11 combinations of viruses were included in the mixed infections. Although human enterovirus is known to be a frequent finding in stool specimens, especially during early childhood, it was found in this study more frequently in nasal swab specimens. Whether this is true, more general, in countries with the high hygiene level remains to be shown.

Nasal cytokine responses to natural colds in asthmatic children

Background

The mechanisms by which viruses induce asthma exacerbations are not well understood.

Objective

We characterized fluctuations in nasal aspirate cytokines during naturally occurring respiratory viral infections in children with asthma.

Methods

Sixteen children underwent home collections of nasal aspirates when they were without cold symptoms and again during self‐reported respiratory illnesses. The presence of viral infection was ascertained by multiplex PCR. Cytokines were measured using multiplex immune assay. mRNA expression for selected markers of viral infection was measured using RT‐PCR. A cumulative respiratory symptom score was calculated for each day of measurement. Generalized estimated equations were used to evaluate associations between viral infection and marker elevation, and between marker elevation and symptom score.

Results

The 16 patients completed a total of 37 weeks of assessment (15 ‘well’ weeks; 22 self‐assessed ‘sick’ weeks). Viral infections were detected in 3 of the ‘well’ weeks and 17 of the ‘sick’ weeks (10 rhinovirus, three coronavirus, two influenza A, two influenza B, two respiratory syncytial virus, one parainfluenza). Compared to virus‐negative well weeks, nasal aspirate IFN‐γ, CXCL8/IL‐8, CXCL10/IP‐10, CCL5/RANTES, CCL11/eotaxin‐1, CCL2/MCP‐1, CCL4/MIP‐1β, CCL7/MCP‐3, and CCL20/MIP3α protein levels increased during virus‐positive sick weeks. Only a subset of cytokines (IFN‐γ, CXCL8, CCL2, CCL4, CCL5, and CCL20) correlated with self‐reported respiratory tract symptoms. While many aspirates were dilute and showed no mRNA signal, viral infection significantly increased the number of samples that were positive for IFN‐λ1, IFN‐λ2/3, TLR3, RIG‐I, and IRF7 mRNA.

Conclusions and clinical relevance

We conclude that in children with asthma, naturally occurring viral infections apparently induce a robust innate immune response including expression of specific chemokines, IFNs, and IFN‐responsive genes.

Rhinovirus-Induced Exacerbations of Asthma and COPD

Over the past two decades, increasing evidence has shown that, in patients with chronic airways disease, viral infection is the most common cause of exacerbation. This review will examine the evidence for viral-induced exacerbations of asthma and chronic obstructive lung disease and the potential mechanisms by which viruses cause exacerbations. Attention will be focused on rhinovirus, the most common cause of respiratory exacerbations. Exacerbations due to rhinovirus, which infects relatively few cells in the airway and does not cause the cytotoxicity of other viruses such as influenza or respiratory syncytial virus, are particularly poorly understood. While the innate immune response likely plays a role in rhinovirus-induced exacerbations, its precise role, either adaptive or maladaptive, is debated. Because current treatment strategies are only partially effective, further research examining the cellular and molecular mechanisms underlying viral-induced exacerbations of chronic airways diseases is warranted.

Respiratory viruses in hospitalized children with influenza-like illness during the h1n1 2009 pandemic in Sweden [corrected]

BACKGROUND

The swine-origin influenza A(H1N1)pdm09 pandemic of 2009 had a slower spread in Europe than expected. The human rhinovirus (HRV) has been suggested to have delayed the pandemic through viral interference. The importance of co-infections over time during the pandemic and in terms of severity of the disease needs to be assessed.

OBJECTIVE

The aim of this study was to investigate respiratory viruses and specifically the presence of co-infections with influenza A(H1N1)pdm09 (H1N1) in hospitalized children during the H1N1 pandemic. A secondary aim was to investigate if co-infections were associated with severity of disease.

METHODS

A retrospective study was performed on 502 children with influenza-like illness admitted to inpatient care at a pediatric hospital in Stockholm, Sweden during the 6 months spanning the H1N1 pandemic in 2009. Respiratory samples were analyzed for a panel of 16 viruses by real-time polymerase chain reaction.

RESULTS

One or more viruses were detected in 61.6% of the samples. Of these, 85.4% were single infections and 14.6% co-infections (2-4 viruses). The number of co-infections increased throughout the study period. H1N1 was found in 83 (16.5%) children and of these 12 (14.5%) were co-infections. HRV and H1N1 circulated to a large extent at the same time and 6.0% of the H1N1-positive children were also positive for HRV. There was no correlation between co-infections and severity of disease in children with H1N1.

CONCLUSIONS

Viral co-infections were relatively common in H1N1 infected hospitalized children and need to be considered when estimating morbidity attributed to H1N1. Population-based longitudinal studies with repeated sampling are needed to improve the understanding of the importance of co-infections and viral interference.

Response to infections in patients with asthma and atopic disease: an epiphenomenon or reflection of host susceptibility?

Associations between respiratory tract infections and asthma inception and exacerbations are well established. Infant respiratory syncytial virus and rhinovirus infections are known to be associated with an increased risk of asthma development, and among children with prevalent asthma, 85% of asthma exacerbations are associated with viral infections. However, the exact nature of this relationship remains unclear. Is the increase in severity of infections an epiphenomenon, meaning respiratory tract infections just appear to be more severe in patients with underlying respiratory disease, or instead a reflection of altered host susceptibility among persons with asthma and atopic disease? The main focus of this review is to summarize the available levels of evidence supporting or refuting the notion that patients with asthma or atopic disease have an altered susceptibility to selected pathogens, as well as discussing the biological mechanism or mechanisms that might explain such associations. Finally, we will outline areas in need of further research because understanding the relationships between infections and asthma has important implications for asthma prevention and treatment, including potential new pathways that might target the host immune response to select pathogens.

Respiratory viral infections in children with asthma: do they matter and can we prevent them?

BACKGROUND

Asthma is a major public health problem with a huge social and economic burden affecting 300 million people worldwide. Viral respiratory infections are the major cause of acute asthma exacerbations and may contribute to asthma inception in high risk young children with susceptible genetic background. Acute exacerbations are associated with decreased lung growth or accelerated loss of lung function and, as such, add substantially to both the cost and morbidity associated with asthma.

DISCUSSION

While the importance of preventing viral infection is well established, preventive strategies have not been well explored. Good personal hygiene, hand-washing and avoidance of cigarette smoke are likely to reduce respiratory viral infections. Eating a healthy balanced diet, active probiotic supplements and bacterial-derived products, such as OM-85, may reduce recurrent infections in susceptible children. There are no practical anti-viral therapies currently available that are suitable for widespread use.

SUMMARY

Hand hygiene is the best measure to prevent the common cold. A healthy balanced diet, active probiotic supplements and immunostimulant OM-85 may reduce recurrent infections in asthmatic children.

Pathogenesis of rhinovirus infection

Since its discovery in 1956, rhinovirus (RV) has been recognized as the most important virus producing the common cold syndrome. Despite its ubiquity, little is known concerning the pathogenesis of RV infections, and some of the research in this area has led to contradictions regarding the molecular and cellular mechanisms of RV-induced illness. In this article, we discuss the pathogenesis of this virus as it relates to RV-induced illness in the upper and lower airway, an issue of considerable interest in view of the minimal cytopathology associated with RV infection. We endeavor to explain why many infected individuals exhibit minimal symptoms or remain asymptomatic, while others, especially those with asthma, may have severe, even life-threatening, complications (sequelae). Finally, we discuss the immune responses to RV in the normal and asthmatic host focusing on RV infection and epithelial barrier integrity and maintenance as well as the impact of the innate and adaptive immune responses to RV on epithelial function.

Targeting airway smooth muscle in airways diseases: an old concept with new twists

Airway smooth muscle (ASM) manifests a hyper-responsive phenotype in airway disorders such as asthma. ASM also modulates immune responses by secreting mediators and expressing cell-surface molecules that promote recruitment of inflammatory cells to the lungs. The aim of the current article is to highlight therapeutics that may modulate ASM responses in airway disorders and exacerbations.

Human rhinovirus species associated with hospitalizations for acute respiratory illness in young US children

BACKGROUND

The contribution of human rhinovirus (HRV) to severe acute respiratory illness (ARI) is unclear.

OBJECTIVE

To assess the association between HRV species detection and ARI hospitalizations.

METHODS

Children <5 years old hospitalized for ARI were prospectively enrolled between December 2003 and April 2005 in 3 US counties. Asymptomatic controls were enrolled between December 2003 and March 2004 and between October 2004 and April 2005 in clinics. Nasal and throat swab samples were tested for HRV and other viruses (ie, respiratory syncytial virus, human metapneumovirus, parainfluenza virus, and influenza virus) by reverse-transcription-polymerase chain reaction, and genetic sequencing identified HRV species and types. HRV species detection was compared between controls and patients hospitalized during months in which controls were enrolled.

RESULTS

A total of 1867 children with 1947 ARI hospitalizations and 784 controls with 790 clinic visits were enrolled and tested for HRV. The HRV-A detection rate among participants ≥24 months old was 8.1% in the hospitalized group and 2.2% in the control group (P = .009), and the HRV-C detection rates among those ≥6 months old were 8.2% and 3.9%, respectively (P = .002); among younger children, the detection rates for both species were similar between groups. The HRV-B detection rate was ≤1%. A broad diversity of HRV types was observed in both groups. Clinical presentations were similar among HRV species. Compared with children infected with other viruses, children with HRV detected were similar for severe hospital outcomes and more commonly had histories or diagnoses of asthma or wheezing.

CONCLUSIONS

HRV-A and HRV-C were associated with ARI hospitalization and serious illness outcomes.

Specific viruses detected in nigerian children in association with acute respiratory disease

Occurrence of different viruses in acute respiratory tract infections of Nigerian children was examined. Respiratory swabs were collected from 246 children referred to hospital clinics because of acute respiratory symptoms from February through May 2009. Validated real-time RT-PCR techniques revealed nucleic acids of at least one virus group in 189 specimens (77%). Human rhinoviruses and parainfluenza viruses were present each in one third of the children. Adenoviruses, enteroviruses, human metapneumovirus, human bocavirus, and influenza C virus were also relatively common. Possibly due to their seasonal occurrence, influenza A and B virus, and respiratory syncytial virus were detected rarely. We conclude that all major groups of respiratory tract viruses are causing illness in Nigerian children.

Highly frequent infections with human rhinovirus in healthy young children: a longitudinal cohort study

BACKGROUND

Human rhinoviruses (HRVs) are an important cause of respiratory tract infections.

OBJECTIVES

We questioned whether the high prevalence rates of HRVs found in epidemiological studies is due to long-term individual continuity or a result of frequent infections with different HRV subtypes.

STUDY DESIGN

In a 6-month winter period 18 healthy controls, aged 0-7 years, were at least sampled every two weeks for HRV-PCR, irrespective of respiratory symptoms. All HRV positive samples were genotyped to determine HRV diversity.

RESULTS

In total 272 samples were collected. HRV was found in 101/272 (37%) samples. Genotyping revealed 27 different HRV subtypes. A median of 3.0 different HRV subtypes was found per child. Re-infections and continuity with identical HRV sequences were observed. The number of HRVs were higher in the youngest age group (p=0.01) and they had more different HRV subtypes (p=0.05) compared to oldest age group.

CONCLUSIONS

We found a high HRV exposition with a considerable diverse population of HRV subtypes in young children. These results have major implications for future research into the pathogenic role of HRV in respiratory diseases. Characterisation of subtypes will be necessary to discriminate between prolonged continuity and re-infections in patients with respiratory diseases.

Repeated virus identification in the airways of patients with mild and severe asthma during prospective follow-up

To cite this article: Turchiarelli V, Schinkel J, Molenkamp R, Foschino Barbaro MP, Carpagnano GE, Spanevello A, Lutter R, Bel EH, Sterk PJ. Repeated virus identification in the airways of patients with mild and severe asthma during prospective follow‐up. Allergy 2011; 66: 1099–1106.

Abstract

Background:  Respiratory viruses may persist in the airways of asthmatics between episodes of clinical worsening. We hypothesized that patients with clinically stable, severe asthma exhibit increased and more prolonged viral presence in the airways as compared to mild asthmatics and healthy controls.

Methods:  Thirty‐five subjects (no cold symptoms >4 weeks) entered a 12‐week prospective study using three groups: clinically stable mild asthma (GINA 2) (n = 12, age 34.1 ± 13.4 year), severe asthma (GINA 4) (n = 12, age 49.3 ± 14.8 year) and healthy controls (n = 11, age 37.9 ± 14.2 year). All subjects underwent spirometry and completed a written questionnaire on asthma symptoms at baseline. Nasal and throat swabs, induced sputum samples, exhaled breath condensate and gelatine‐filtered expired air were analysed at 0, 6 and 12 weeks by a multiplex real‐time PCR assay for 14 respiratory viruses using adequate positive and negative controls.

Results:  Thirty‐two of 525 patient assessments (6%) showed a virus‐positive sample. Among the 14 respiratory viruses examined, HRV, adenovirus, respiratory syncytial virus, parainfluenza 3&4, human bocavirus, influenza B and coronavirus were detected. When combining all sampling methods, on average 18% of controls and 30% of mild and severe asthmatics were virus positive, which was not different between the groups (P = 0.34). The longitudinal data showed a changing rather than persistent viral presence over time.

Conclusion:  Patients with clinically stable asthma and healthy controls have similar detection rates of respiratory viruses in samples from nasopharynx, sputum and exhaled air. This indicates that viral presence in the airways of stable (severe) asthmatics varies over time rather than being persistent.