Distinction between rhinovirus-induced acute asthma and asthma-augmented influenza infection

Effects of climate and environmental factors on childhood and adolescent asthma: A systematic review based on spatial and temporal analysis evidence

BACKGROUND

Asthma is a prevalent chronic respiratory disease among children, influenced by various climate and environmental factors. Despite its prevalence, the specific effects of these factors on asthma remain unclear. This study aims to systematically assess the epidemiological evidence using spatial and temporal methods on the impact of climate and environmental factors on childhood asthma.

METHODS

A systematic review was conducted to analyse the impact of climate and environmental factors on childhood asthma and wheezing, focusing on spatial and temporal trends. Searches were carried out in PubMed, Embase, and CINAHL databases for studies published from January 2000 to April 2024, using key search terms 'asthma/wheezing', 'extreme weather, 'green space', 'air pollution' and 'spatial or temporal analyses".

RESULTS

The systematic review analysed 28 studies, with six employing spatial and 22 using temporal analysis methods; however, none incorporated spatio-temporal analysis in their models. The findings reveal that extreme weather events, including heatwaves and heavy rainfall, elevate childhood asthma risks across various climates, with significant effects observed during summer and winter months. Dust storms in arid and subtropical regions are linked to immediate spikes in hospital admissions due to asthma exacerbations. The effects of green spaces on childhood asthma are mixed, with some studies indicating protective effects while others suggest increased risks, influenced by local environmental factors. Air pollutants such as PM2.5, NO2, and ozone can exacerbate asthma symptoms and along with other environmental factors, contribute to seasonal effects. High temperatures generally correlate with increased asthma risks, though the effects vary by age, sex, and climate.

CONCLUSION

Future research should integrate spatial and temporal methods to better understand the effects of environmental and climate changes on childhood asthma.

Bacteria and viruses and their role in the preschool wheeze to asthma transition

Wheezing is the cardinal symptom of asthma; its presence early in life, mostly caused by viral infections, is a major risk factor for the establishment of persistent or recurrent disease. Early-life wheezing and asthma exacerbations are triggered by common respiratory viruses, mainly rhinoviruses (RV), and to a lesser extent, respiratory syncytial virus, parainfluenza, human metapneumovirus, coronaviruses, adenoviruses, influenza, and bocavirus. The excess presence of bacteria, several of which are part of the microbiome, has also been identified in association with wheezing and acute asthma exacerbations, including haemophilus influenza, streptococcus pneumoniae, moraxella catarrhalis, mycoplasma pneumoniae, and chlamydophila pneumonia. While it is not clear when asthma starts, its characteristics develop over time. Airway remodeling already appears between the ages of 1 and 3 years of age even prior to the presence of atopic inflammation or an asthma diagnosis. The role of genetic defect or variations hampering the airway epithelium in response to environmental stimuli and severe disease morbidity are now considered as major determinants for early structural changes. Repeated viral infections can induce and perpetuate airway hyperresponsiveness. Allergic sensitization, that often precedes infection-induced wheezing, shifts inflammation toward type-2, while common respiratory infections themselves promote type-2 inflammation. Nevertheless, most children who wheeze with viral infections during infancy and during preschool years do not develop persistent asthma. Multiple factors, including illness severity, viral etiology, allergic sensitization, and the exposome, are associated with disease persistence. Here, we summarize current knowledge and developments in infection epidemiology of asthma in children, describing the known impact of each individual agent and mechanisms of transition from recurrent wheeze to asthma.

Prevalence and clinical implications of respiratory viruses in asthma during stable disease state and acute attacks: Protocol for a meta-analysis

INTRODUCTION

Viruses are detected in over 50% of acute asthma attacks and in a notable proportion of patients with asthma during stable disease state They are associated with worse outcomes. We will conduct a series of systematic reviews and meta-analyses to quantify the prevalence and clinical burden of various respiratory viruses in stable asthma and acute asthma attacks. In addition, we will assess the viral loads of respiratory viruses during stable and acute asthma, to explore whether viral load could differentiate attacks triggered by viruses versus those where viruses are present as "innocent bystanders".

MATERIALS AND METHODS

Based on a prospectively registered protocol (PROSPERO, ID: CRD42023375108) and following standard methodology recommended by Cochrane, we will systematically search Medline/PubMed, EMBASE, the Cochrane Library and relevant conference proceedings for studies assessing the prevalence or clinical burden of respiratory viruses in asthma. Methodological rigour of the included studies will be appraised using a tool specific for prevalence studies and the Newcastle-Ottawa Scale respectively. In anticipation of significant clinical and methodological heterogeneity, we will conduct random effect meta-analyses. For evaluating the prevalence of viruses, we will perform meta-analyses of proportions using the inverse variance method, and the Freeman-Tukey transformation. We will conduct meta-regression analyses for exploring heterogeneity.

CONCLUSION

We envisage that these systematic reviews and meta-analyses will quantify the prevalence and burden of respiratory viruses in stable and acute asthma and will drive future research and clinical practice.

Respiratory eukaryotic virome expansion and bacteriophage deficiency characterize childhood asthma

Asthma development and exacerbation is linked to respiratory virus infections. There is limited information regarding the presence of viruses during non-exacerbation/infection periods. We investigated the nasopharyngeal/nasal virome during a period of asymptomatic state, in a subset of 21 healthy and 35 asthmatic preschool children from the Predicta cohort. Using metagenomics, we described the virome ecology and the cross-species interactions within the microbiome. The virome was dominated by eukaryotic viruses, while prokaryotic viruses (bacteriophages) were independently observed with low abundance. Rhinovirus B species consistently dominated the virome in asthma. Anelloviridae were the most abundant and rich family in both health and asthma. However, their richness and alpha diversity were increased in asthma, along with the co-occurrence of different Anellovirus genera. Bacteriophages were richer and more diverse in healthy individuals. Unsupervised clustering identified three virome profiles that were correlated to asthma severity and control and were independent of treatment, suggesting a link between the respiratory virome and asthma. Finally, we observed different cross-species ecological associations in the healthy versus the asthmatic virus-bacterial interactome, and an expanded interactome of eukaryotic viruses in asthma. Upper respiratory virome "dysbiosis" appears to be a novel feature of pre-school asthma during asymptomatic/non-infectious states and merits further investigation.

Transcriptomics of rhinovirus persistence reveals sustained expression of RIG-I and interferon-stimulated genes in nasal epithelial cells in vitro

BACKGROUND

Human rhinoviruses (HRVs) are frequently associated with asthma exacerbations, and have been found in the airways of asthmatic patients. While HRV-induced acute infection is well-documented, it is less clear whether the nasal epithelium sustains prolonged HRV infections along with the associated activation of host immune responses.

OBJECTIVE

To investigate sustainably regulated host responses of human nasal epithelial cells (hNECs) during HRV persistence.

METHODS

Using a time-course study, HRV16 persistence and viral replication dynamics were established using an in vitro infection model of hNECs. RNA sequencing was performed on hNECs in the early and late stages of infection at 3 and 14 days post-infection (dpi), respectively. The functional enrichment of differentially expressed genes (DEGs) was evaluated using gene ontology (GO) and Ingenuity pathway analysis.

RESULTS

HRV RNA and protein expression persisted throughout prolonged infections, even after decreased production of infectious virus progeny. GO analysis of unique DEGs indicated altered regulation of pathways related to ciliary function and airway remodeling at 3 dpi and serine-type endopeptidase activity at 14 dpi. The functional enrichment of shared DEGs between the two time-points was related to interferon (IFN) and cytoplasmic pattern recognition receptor (PRR) signaling pathways. Validation of the sustained regulation of candidate genes confirmed the persistent expression of RIG-I and revealed its close co-regulation with interferon-stimulated genes (ISGs) during HRV persistence.

CONCLUSIONS

The persistence of HRV RNA does not necessarily indicate an active infection during prolonged infection. The sustained expression of RIG-I and ISGs in response to viral RNA persistence highlights the importance of assessing how immune-activating host factors can change during active HRV infection and the immune regulation that persists thereafter.

Mediterranean-Type Diets as a Protective Factor for Asthma and Atopy

We are currently riding the second wave of the allergy epidemic, which is ongoing in affluent societies, but now also affecting developing countries. This increase in the prevalence of atopy/asthma in the Western world has coincided with a rapid improvement in living conditions and radical changes in lifestyle, suggesting that this upward trend in allergic manifestations may be associated with cultural and environmental factors. Diet is a prominent environmental exposure that has undergone major changes, with a substantial increase in the consumption of processed foods, all across the globe. On this basis, the potential effects of dietary habits on atopy and asthma have been researched rigorously, but even with a considerable body of evidence, clear associations are far from established. Many factors converge to obscure the potential relationship, including methodological, pathophysiological and cultural differences. To date, the most commonly researched, and highly promising, candidate for exerting a protective effect is the so-called Mediterranean diet (MedDi). This dietary pattern has been the subject of investigation since the mid twentieth century, and the evidence regarding its beneficial health effects is overwhelming, although data on a correlation between MedDi and the incidence and severity of asthma and atopy are inconclusive. As the prevalence of asthma appears to be lower in some Mediterranean populations, it can be speculated that the MedDi dietary pattern could indeed have a place in a preventive strategy for asthma/atopy. This is a review of the current evidence of the associations between the constituents of the MedDi and asthma/atopy, with emphasis on the pathophysiological links between MedDi and disease outcomes and the research pitfalls and methodological caveats which may hinder identification of causality. MedDi, as a dietary pattern, rather than short-term supplementation or excessive focus on single nutrient effects, may be a rational option for preventive intervention against atopy and asthma.

Protective effect of inhaled corticosteroid on children with asthma with Mycoplasma pneumoniae pneumonia

BACKGROUND

The aim of this study was to determine the differences in the characteristics of Mycoplasma pneumoniae pneumonia (MPP) in children with and without asthma and in children with asthma with and without inhaled corticosteroid (ICS) therapy in order to determine the risk factors for asthma exacerbation and the effect of regular ICS therapy on children with asthma with MPP.

MATERIALS AND METHODS

Children with MPP were divided into two groups according to whether they had a history of asthma. Children with asthma were further divided into an ICS therapy group and a group without ICS therapy. The clinical characteristics, laboratory test results, and pulmonary images were compared between the children with and without asthma. Differences in the severity of acute exacerbation were compared between the children with asthma in the ICS therapy and without ICS therapy groups. Multivariable logistic regression was used to determine the risk factors for exacerbation of MPP in children with asthma.

RESULTS

In children with MPP, the differences in the eosinophil counts; total immunoglobulin E (IgE), C-reactive protein, procalcitonin (PCT), and lactate dehydrogenase (LDH) levels; and fever duration, wheezing, extrapulmonary complications, oxygen saturation < 92%, severe pneumonia, pleural effusion, co-infection with other pathogens, and lobar pneumonia between children with and without asthma were statistically significant. Among children with asthma with MPP, those in the ICS therapy group were less likely to experience an exacerbation, and exacerbations were less severe than those in the without ICS therapy group. The multivariable logistic regression analysis showed that the ICS therapy was an independent protective factor against exacerbation.

CONCLUSION

Among children with MPP, the chance of wheezing was higher in children with asthma than in children without asthma. The ICS therapy was a protective factor against exacerbation in children with asthma with MPP.

Whole transcriptome analysis of high and low IFN-α producers reveals differential response patterns following rhinovirus stimulation

Objectives

Viral respiratory infections cause considerable morbidity and economic loss. While rhinoviruses (RV) typically cause little more than the common cold, they can produce severe infections and disease exacerbations in susceptible individuals, such as those with asthma. Variations in the regulation of key antiviral cytokines, particularly type I interferon (IFN‐α and IFN‐β), may contribute to RV susceptibility. To understand this variability, we compared the transcriptomes of high and low type I IFN producers.

Methods

Blood mononuclear cells from 238 individuals with or without asthma were cultured in the presence or absence of RV. Those samples demonstrating high or low RV‐stimulated IFN‐α production (N = 75) underwent RNA‐sequencing.

Results

Gene expression patterns were similar in samples from healthy participants and those with asthma. At baseline, the high IFN‐α producer group showed higher expression of genes associated with plasmacytoid dendritic cells, the innate immune response and vitamin D activation, but lower expression of oxidative stress pathways than the low IFN‐α producer group. After RV stimulation, the high IFN‐α producer group showed higher expression of genes found in immune response biological pathways and lower expression of genes linked to developmental and catabolic processes when compared to the low IFN‐α producer group.

Conclusions

These differences suggest that the high IFN‐α group has a higher level of immune system readiness, resulting in a more intense and perhaps more focussed pathogen‐specific immune response. These results contribute to a better understanding of the variability in type I IFN production between individuals.

A real-life comparative effectiveness study into the addition of antibiotics to the management of asthma exacerbations in primary care

BACKGROUND

Asthma exacerbations are major contributors to asthma morbidity and mortality. They are usually managed with bronchodilators and oral corticosteroids (OCS), but clinical trial evidence suggests that antibiotics could be beneficial. We aimed to assess whether treatment of asthma exacerbations with antibiotics in addition to OCS improved outcomes in larger, more representative routine-care populations.

METHOD

A retrospective comparative effectiveness study into managing asthma exacerbations with OCS alone versus OCS plus antibiotics was conducted using the Optimum Patient Care Research Database. The dataset included 28 637 patients; following propensity score matching 20 024 adults and 4184 children were analysed.

RESULTS

Antibiotics in addition to OCS were prescribed for the treatment of asthma exacerbations in 45% of adults and 32% of children. Compared to OCS alone, OCS plus antibiotics was associated with reduced risk of having an asthma/wheeze consultation in the following 2 weeks (children hazard ratio (HR) 0.84 (95% CI 0.73-0.96), p=0.012; adults HR 0.86 (95% CI 0.81-0.91), p<0.001), but an increase in risk of a further OCS prescription for a new/ongoing exacerbation within 6 weeks in adults (HR 1.11 (95% CI 1.01-1.21), p=0.030), but not children. Penicillins, but not macrolides, were associated with a reduction in the odds of a subsequent asthma/wheeze consultation compared to OCS alone, in both adults and children.

CONCLUSION

Antibiotics were frequently prescribed in relation to asthma exacerbations, contrary to guideline recommendations. Overall, the routine addition of antibiotics to OCS in the management of asthma exacerbations appeared to confer little clinical benefit, especially when considering the risks of antibiotic overuse.

Clinical correlates of rhinovirus infection in preschool asthma

Background

Investigation of preschool asthma is important since not all children outgrow their illness during this age. Data are scarce on the role of rhinovirus (RV) infections in this patient group.

Objectives

To investigate the role of RV infections in preschool asthma: (i) susceptibility factors, (ii) clinical course, and (iii) medium‐term outcome.

Methods

A total of 130 asthmatic children aged 4‐6 years from the multinational PreDicta cohort were prospectively followed for a 12‐month period. Allergy tests and a standard health questionnaire were carried out at study entry. Respiratory virus presence in nasopharyngeal washes was studied at illness visits and at 3 scheduled visits.

Results

At study entry, mean age of the children was 5.3 years. Of 571 visits, 54% were positive for any virus and 39% for RV. Patient characteristics were only assessed with RV infection due to low number of other viruses. The use of supplementary vitamin D was inversely associated with RV infection (P < .05). RV infection was associated with more severe course of acute illness in terms of more severe nighttime coughing, more sleep disturbances, and more days with runny nose (all P < .05). RV infection was also associated with more severe disease course during the 12‐month follow‐up in terms of more nights with awakenings and more days of exercise‐related symptoms (both P < .05).

Conclusions

Vitamin D supplementation may have an anti‐rhinovirus effect. Both short‐ and medium‐term outcomes suggest RV infection to be an important clinical marker of instable preschool asthma.

Developments in the mechanisms of allergy in 2018 through the eyes of Clinical and Experimental Allergy, Part I

In the first of two linked articles, we describe the development in the mechanisms underlying allergy as described by Clinical & Experimental Allergy and other journals in 2018. Experimental models of allergic disease, basic mechanisms and clinical mechanisms are all covered.

Impact of COVID-19 on Pediatric Asthma: Practice Adjustments and Disease Burden

Background

It is unclear whether asthma may affect susceptibility or severity of coronavirus disease 2019 (COVID-19) in children and how pediatric asthma services worldwide have responded to the pandemic.

Objective

To describe the impact of the COVID-19 pandemic on pediatric asthma services and on disease burden in their patients.

Methods

An online survey was sent to members of the Pediatric Asthma in Real Life think tank and the World Allergy Organization Pediatric Asthma Committee. It included questions on service provision, disease burden, and the clinical course of confirmed cases of COVID-19 infection among children with asthma.

Results

Ninety-one respondents, caring for an estimated population of more than 133,000 children with asthma, completed the survey. COVID-19 significantly impacted pediatric asthma services: 39% ceased physical appointments, 47% stopped accepting new patients, and 75% limited patients' visits. Consultations were almost halved to a median of 20 (interquartile range, 10-25) patients per week. Virtual clinics and helplines were launched in most centers. Better than expected disease control was reported in 20% (10%-40%) of patients, whereas control was negatively affected in only 10% (7.5%-12.5%). Adherence also appeared to increase. Only 15 confirmed cases of COVID-19 were reported among the population; the estimated incidence is not apparently different from the reports of general pediatric cohorts.

Conclusions

Children with asthma do not appear to be disproportionately affected by COVID-19. Outcomes may even have improved, possibly through increased adherence and/or reduced exposures. Clinical services have rapidly responded to the pandemic by limiting and replacing physical appointments with virtual encounters.

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.

MicroRNAs in Asthma and Respiratory Infections: Identifying Common Pathways

MicroRNAs (miRs) are single-stranded RNAs of 18-25 nucleotides. These molecules regulate gene expression at the post-transcriptional level; several of these are differentially expressed in asthma as well as in viral acute respiratory infections (ARIs), the main triggers of acute asthma exacerbations. In recent years, miRs have been studied in order to discover drug targets as well as biomarkers for diagnosis, disease severity and prognosis. We describe recent findings on miR expression and function in asthma and their role in the regulation of viral ARIs, according to cell tissue specificity and asthma severity. By combining the above information, we identify miRs that may be important in virus-induced asthma exacerbations. This is the first attempt to link miR profiles of asthmatic patients and ARI-induced miRs, addressing the question of whether there might be a specific miR deficit in asthmatic subjects that make them more susceptible and/or reactive to infection.

RNA Sequencing of H3N2 Influenza Virus-Infected Human Nasal Epithelial Cells from Multiple Subjects Reveals Molecular Pathways Associated with Tissue Injury and Complications

The human nasal epithelium is the primary site of exposure to influenza virus, the initiator of host responses to influenza and the resultant pathologies. Influenza virus may cause serious respiratory infection resulting in major complications, as well as severe impairment of the airways. Here, we elucidated the global transcriptomic changes during H3N2 infection of human nasal epithelial cells from multiple individuals. Using RNA sequencing, we characterized the differentially-expressed genes and pathways associated with changes occurring at the nasal epithelium following infection. We used in vitro differentiated human nasal epithelial cell culture model derived from seven different donors who had no concurrent history of viral infections. Statistical analysis highlighted strong transcriptomic signatures significantly associated with 24 and 48 h after infection, but not at the earlier 8-h time point. In particular, we found that the influenza infection induced in the nasal epithelium early and altered responses in interferon gamma signaling, B-cell signaling, apoptosis, necrosis, smooth muscle proliferation, and metabolic alterations. These molecular events initiated at the infected nasal epithelium may potentially adversely impact the airway, and thus the genes we identified could serve as potential diagnostic biomarkers or therapeutic targets for influenza infection and associated disease management.

Emergency department asthma diagnosis risk associated with the 2012 heat wave and drought in Douglas County NE, USA

BACKGROUND

Global climate change concerns are forcing local public health agencies to assess potential disease risk.

OBJECTIVE

Determine if risk of an emergency department asthma diagnosis in Douglas County, NE, was higher during the 2012 heatwave compared to 2011.

METHODS

Retrospective, observational, case-control design selecting subjects from 2011 and 2012 emergency department (ED) admissions. Risk was estimated by conditional logistic regression.

RESULTS

The asthma ED risk estimate was 1.23 (95%CI = 0.96-1.57) times higher in 2012 than 2011, for the same calendar period. Asthma ED diagnosis risk was 3.37 (95%CI = 2.27-4.17) times higher among subjects <19years old compared to older subjects, and 3.25 (95%CI = 2.63-4.02) times higher among African-Americans than non-African-Americans, adjusted for heatwave exposure. Absolute humidity appears inversely related to asthma diagnosis risk ( χ2 = 16.6; p < 0.001).

CONCLUSION

Asthma ED diagnosis risk was not significantly higher in 2012 compared to 2011. Risk was elevated among subjects less than 19years old, and among African Americans; adjusted for heatwave exposure.

Exacerbations of chronic respiratory diseases

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