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

Virological Profile of Asthma Exacerbation in Children: A Hospital-Based Retrospective Study

Introduction Viruses are the most common triggering factors for asthma exacerbation during the autumn and winter seasons. Viruses, such as influenza A and rhinovirus, play a major role in the occurrence of severe exacerbation of asthma. This association between viral infection and asthma exacerbation in children is a result of the antiviral response of the immune system and various anti-inflammatory phenomena. In this work, we aimed to identify the virological profile of asthma exacerbation in children and analyze the correlation between viral infection type and the severity of exacerbation. Materials and methods This retrospective study was conducted from January 2016 to January 2024. The study included children hospitalized for asthma exacerbation associated with signs of viral-like respiratory infection with positive virological testing by multiplex real-time polymerase chain reaction or rapid test in the case of influenza A or respiratory syncytial virus (RSV). Data analysis was performed with Microsoft Excel and SPSS software using a previously established data collection sheet Results Thirty cases were collected for the study period. The mean age of the patients was 4 years and 8 months, with a male-to-female ratio of 3.3. Eighteen patients were known to have asthma, of which nine had uncontrolled asthma, and exacerbation was inaugural in 12 patients. Viral shedding was found in 14 patients. A viral agent was found in all patients, with coinfection of two or more viruses in three patients. The viruses found were influenza A (18 cases), coupled rhinovirus/enterovirus (eight cases), RSV (eight cases), human metapneumovirus (three patients), and parainfluenza type IV in only one inaugural patient. Asthma exacerbation was severe in 20 patients, moderate in eight patients, and two patients had severe acute asthma requiring intensive care management. We noted a higher frequency of severe exacerbation among those with an influenza A viral infection. All patients with RSV infection exhibited moderate exacerbation. No other significant correlation between asthma severity and other types of viruses was found. Conclusions Our results demonstrate the major role played by viruses in triggering asthma exacerbation, primarily influenza virus, followed by enterovirus, rhinovirus, RSV, and metapneumovirus. Larger-scale studies should be carried out to establish a more complete virological profile and further investigate the viral factor in the management of asthma in children.

Suppressed pediatric asthma hospitalizations during the COVID-19 pandemic in Japan, from a national survey

BACKGROUND

Acute asthma exacerbation in children is often caused by respiratory infections. In this study, a coordinated national surveillance system for acute asthma hospitalizations and causative respiratory infections was established. We herein report recent trends in pediatric acute asthma hospitalizations since the COVID-19 pandemic in Japan.

METHODS

Thirty-three sentinel hospitals in Japan registered all of their hospitalized pediatric asthma patients and their causal pathogens. The changes in acute asthma hospitalization in children before and after the onset of the COVID-19 pandemic and whether or not COVID-19 caused acute asthma exacerbation were investigated.

RESULTS

From fiscal years 2010-2019, the median number of acute asthma hospitalizations per year was 3524 (2462-4570), but in fiscal years 2020, 2021, and 2022, the numbers were 820, 1,001, and 1,026, respectively (the fiscal year in Japan is April to March). This decrease was observed in all age groups with the exception of the 3- to 6-year group. SARS-CoV-2 was evaluated in 2094 patients from fiscal years 2020-2022, but the first positive case was not detected until February 2022. Since then, only 36 of them have been identified with SARS-CoV-2, none of which required mechanical ventilation. Influenza, RS virus, and human metapneumovirus infections also decreased in FY 2020. In contrast, 24% of patients had not been receiving long-term control medications before admission despite the severity of bronchial asthma.

CONCLUSION

SARS-CoV-2 was hardly detected in children with acute asthma hospitalization during the COVID-19 pandemic. This result indicated that SARS-CoV-2 did not induce acute asthma exacerbation in children. Rather, infection control measures implemented against the pandemic may have consequently reduced other respiratory virus infections and thus acute asthma hospitalizations during this period. However, the fact that many hospitalized patients have not been receiving appropriate long-term control medications is a major problem that should be addressed.

Incidence and causative agent distribution of viral-induced paediatric asthma exacerbations under strict infection control measures: a single-centre retrospective study in Japan

BACKGROUND

The prevalence of respiratory viruses in children changed under strict infection control measures during the coronavirus disease 2019 (COVID-19) outbreak. In this study, we investigated the frequency of viral detection in the nasopharynx of paediatric patients with asthma exacerbations requiring hospitalization during the COVID-19 pandemic, as well as the distribution of causative viruses.

METHODS

We included paediatric patients admitted for asthma exacerbations between November 2020 and December 2022 at a single centre in Kobe, Japan. Demographic, clinical, and laboratory data were collected from their medical records and using additional questionnaires. All patients enrolled in this study met the diagnostic criteria for asthma exacerbations outlined in the Japanese Pediatric Guideline for the Treatment and Management of Bronchial Asthma 2020. Statistical differences were calculated using univariate analyses (chi-square or Mann‒Whitney U test).

RESULTS

We enrolled 203 children hospitalized for asthma attacks and collected nasopharyngeal samples from 189 patients. The median patient age was 3.0 years. Asthma severity was classified as mild (4.0%), moderate (82.3%), or severe (13.8%). The proportion of viral respiratory infections was 95.2% (180/189). The rate of patients with multiple viral infections was 20.6% (39/189). The most frequently detected pathogens were rhinovirus and enterovirus (RV/EV) at 69.3% (131/189), allowing for duplicate detection, followed by respiratory syncytial virus (RSV) at 28.6% (54/189). We also detected RV/EV almost every month compared to RSV and other viruses. In addition, RV/EV-positive patients were significantly older (p = 0.033), exhibited higher WBC counts (p < 0.001) and higher Eos counts (p < 0.001), had elevated total IgE levels (p < 0.001) and house dust mite-specific IgE levels (p = 0.019), had a shorter duration of hospitalization (p < 0.001), and had a shorter duration of oxygen therapy (p < 0.001). In patients positive for RV/EV, the use of ICSs significantly reduced the severity of the condition (p < 0.001).

CONCLUSION

Even under strict infection control measures, respiratory viruses were detected in the nasopharynx of almost all paediatric patients who had asthma exacerbations requiring hospitalization.

Mechanisms of Long-Term Persistence of Mycoplasmas in Children with Asthma

Improving the management of children with asthma associated with mycoplasma infection is important. Aim: To study the duration of the persistence of antigens, and DNA in a free state, in the structures of circulating immune complexes (CICs) and living cells of Mycoplasma pneumoniae (Mpn) and Mycoplasma hominis (Mh) in children with asthma. In total, 205 children with asthma from 1 to 14 years were observed. The reaction of aggregate-hemagglutination (AHAA), the direct immunofluorescence reaction (DIF), the reaction of the polymerase chain reaction (PCR), and the culture method were used. In addition, 47 children were re-examined 1.5 months after the treatment of mycoplasma infection with azithromycin. The number of samples positive for antigens and DNA in the free state and in the structures of CICs significantly decreased. Then, 50 blood serum samples containing Mh antigens, and 50 samples containing Mpn antigens were analyzed by culture method. Mh was isolated in 21 (65.5%) of 32 samples containing DNA. Mpn was isolated from antigen-positive samples in nine cases. The presented data indicate the long-term persistence of antigens, and DNA of mycoplasma cells in the free state, in the structure of CICs, as well as in the form of "microcolonies". A high level of CICs can be used to predict the course of the disease and the response to therapy.

The efficacy and safety of azithromycin in treatment for childhood asthma: A systematic review and meta-analysis

BACKGROUND

Azithromycin (AZI) is increasingly used for childhood asthma despite limited and inconsistent data. We aimed to evaluate the efficacy and safety of AZI in childhood asthma.

METHODS

We searched seven databases to include randomized controlled trials (RCTs) of AZI in the treatment of childhood asthma. Four reviewers independently screened the records. Risk of Bias 2 was used to assess the quality of RCTs. Risk ratios with 95% confidence interval (CI) from dichotomous outcomes, and mean difference (MD) with 95% CI from continuous outcomes were pooled.

RESULTS

We included 19 eligible reports from 17 studies. The prevalence of exacerbations in AZI + budesonide (BUD) + β₂ agonist (BA) group was lower than BUD + BA group (four [13%] vs. 19 [63%], p < 0.05) in 6- 14 years old children with chronic persistent asthma. AZI plus antiasthma drugs (AADs) could improve the posttreatment childhood asthma control test score (MD = 2.97; 95% CI, 2.39-3.54) compared to AADs alone in children with chronic persistent asthma. AZI plus AADs could improve posttreatment forced expiratory volume in 1 s of predicted value/forced vital capacity % (MD = 10.24%; 95% CI, 6.44%-14.03%) and posttreatment peak expiratory flow % of predicted value (MD = 7.00%; 95% CI, 2.53%-11.47%) compared to AADs alone in children with chronic persistent asthma. The most common adverse reactions of AZI combined with other drugs were gastrointestinal reactions.

CONCLUSIONS

AZI may be beneficial in improving some clinical symptoms and lung functions in older asthma children (over 6 years old) with persistent asthma. But it still requires further research.

RSV Epidemiology in Australia Before and During COVID-19

COVID-19 public health measures altered respiratory syncytial virus (RSV) epidemiology. We examined age-stratified trends in RSV-related disease in Australian children in 2020 compared with previous years.

Disease burden of respiratory syncytial virus infection in the pediatric population in Japan

INTRODUCTION

Respiratory syncytial virus (RSV) is one of the most common causes of lower respiratory tract infections in children aged <5 years and is associated with long-term respiratory morbidities such as recurrent wheezing and asthma, decreased lung function, and allergic sensitization. The objective of this review was to evaluate the epidemiology and burden of RSV infection in the pediatric population in Japan.

METHODS

Studies indexed in PubMed and ICHUSHI databases during January 2010-December 2020 were manually reviewed. Data on proportion of RSV infections, seasonality, length of stay (LoS), mortality, medical expenses, and palivizumab use were extracted from the selected articles.

RESULTS

Ninety-three articles were included (PubMed, 64; ICHUSHI, 29). The proportion of patients/samples with an RSV infection was 5.5%-66.7%, and 6.0%-29.9% in the inpatient and outpatient departments, respectively. RSV infections generally occurred during autumn/winter; however, recently the peak has shifted to summer. The LoS was variable and depended on factors such as age, infection severity, wheezing, and RSV subgroups. Mortality rates varied from <1% to 19% depending on the infection severity. The average daily hospitalization and intensive care unit cost was JPY 34,548 while intensive care unit incurred an additional cost of JPY 541,293. Palivizumab was indicated for high-risk infants and 0%-3% of patients required hospitalization despite palivizumab use.

CONCLUSIONS

RSV imposes a significant burden on the Japanese healthcare system, suggesting a need to create awareness among caregivers of children, pregnant women and healthcare professionals to ensure early recognition of infection and adequate treatment or prophylaxis.

Risk Factors for Pediatric Asthma Readmissions: A Systematic Review

OBJECTIVE

To systematically review the literature on pediatric asthma readmission risk factors.

STUDY DESIGN

We searched PubMed/MEDLINE, CINAHL, Scopus, PsycINFO, and Cochrane Central Register of Controlled Trials for published articles (through November 2019) on pediatric asthma readmission risk factors. Two authors independently screened titles and abstracts and consensus was reached on disagreements. Full-text articles were reviewed and inclusion criteria applied. For articles meeting inclusion criteria, authors abstracted data on study design, patient characteristics, and outcomes, and 4 authors assessed bias risk.

RESULTS

Of 5749 abstracts, 74 met inclusion criteria. Study designs, patient populations, and outcome measures were highly heterogeneous. Risk factors consistently associated with early readmissions (≤30 days) included prolonged length of stay (OR range, 1.1-1.6) and chronic comorbidities (1.7-3.2). Risk factors associated with late readmissions (>30 days) included female sex (1.1-1.6), chronic comorbidities (1.5-2), summer discharge (1.5-1.8), and prolonged length of stay (1.04-1.7). Across both readmission intervals, prior asthma admission was the most consistent readmission predictor (1.3-5.4).

CONCLUSIONS

Pediatric asthma readmission risk factors depend on the readmission interval chosen. Prior hospitalization, length of stay, sex, and chronic comorbidities were consistently associated with both early and late readmissions.

TRIAL REGISTRATION

CRD42018107601.

The role of the environment in shaping the trends of childhood asthma - An Asian perspective

Asthma has now become one of the most common atopic disorders not only in developed countries but also in many developing countries. The etiology is likely due to a complex interaction between genetic and environmental factors. In many Asian countries, the prevalence of asthma has also been documented by validated instruments to be increasing rapidly over the past two decades. However, studies in rural areas in Asia with a traditional farming environment revealed markedly lower asthma prevalence when compared with residents in nearby cities despite having similar genetic background. Among the environmental factors implicated in the pathogenesis of asthma, air pollution, dietary patterns, viral infections, and early microbial exposure have been studied extensively around the world. Asia provides many opportunities to study these potential factors as there are many ethnic groups living in distinctly different environments. The understanding of the roles of these factors in affecting the early immune system and subsequent development of asthma will enable us to develop potential primary preventive strategies against a disease which affects millions worldwide.

Exacerbation-Prone Asthma: A Biological Phenotype or a Social Construct

Asthma is a complex syndrome with multiple phenotypes and endotypes. Asthma exacerbations are not only the clearest indictor of the morbidity of asthma and of the risk for mortality due to asthma, but also comprise a significant amount of the cost to care for poorly controlled asthma. There continues to be significant disparity in the prevalence, mortality, and morbidity due to asthma. Patients with asthma who suffer recurrent exacerbations are considered to have exacerbation-prone asthma (EPA). Efforts to characterize patients with frequent exacerbations show that the etiology is likely multifactorial. Research to determine the intrinsic risk factors for EPA include studies of both genetic and inflammatory biomarkers. External factors contributing to exacerbations have been extensively reviewed and include viral infection, environmental exposures, air pollution, and psychosocial and economic barriers to optimizing health. It is likely that EPA occurs when patients who have an increased underlying intrinsic/biological risk are placed in a given exposome (environments with a variety of exposures and triggers including allergens, pollution, stress, barriers, and occupational exposures). It is the social construct combined with underlying biology that frequently drives an EPA phenotype.

Ruxolitinib inhibits poly(I:C) and type 2 cytokines-induced CCL5 production in bronchial epithelial cells: A potential therapeutic agent for severe eosinophilic asthma

Rationale

Severe eosinophilic asthma is characterized by airway eosinophilia and corticosteroid‐resistance, commonly overlapping with type 2 inflammation. It has been reported that chemokine (C‐C motif) ligand 5 (CCL5) is involved in the exacerbation of asthma by RNA virus infections. Indeed, treatment with a virus‐associated ligand and a T helper type 2 cell (Th2) cytokine can synergistically stimulate CCL5 production in bronchial epithelial cells. We aimed to evaluate the mechanisms underlying CCL5 production in this in vitro model and to assess the potential of Janus kinase 1 (JAK1) as a novel therapeutic target via the use of ruxolitinib.

Methods

We stimulated primary normal human bronchial epithelial (NHBE) cells and BEAS‐2B cells with poly(I:C) along with interleukin‐13 (IL‐13) or IL‐4, and assessed CCL5 production. We also evaluated the signals involved in virus‐ and Th2‐cytokine‐induced CCL5 production and explored a therapeutic agent that attenuates the CCL5 production.

Results

Poly(I:C) stimulated NHBE and BEAS‐2B cells to produce CCL5. Poly(I:C) and IL‐13 increased CCL5 production. Poly(I:C)‐induced CCL5 production occurred via the TLR3–IRF3 and IFNAR/JAK1–phosphoinositide 3‐kinase (PI3K) pathways, but not the IFNAR/JAK1–STATs pathway. In addition, IL‐13 did not augment poly(I:C)‐induced CCL5 production via the canonical IL‐13R/IL‐4R/JAK1–STAT6 pathway but likely via subsequent TLR3‐IRF3‐IFNAR/JAK1‐PI3K pathways. JAK1 was identified to be a potential therapeutic target for severe eosinophilic asthma. The JAK1/2 inhibitor, ruxolitinib, was demonstrated to more effectively decrease CCL5 production in BEAS‐2B cells than fluticasone propionate.

Conclusion

We have demonstrated that JAK1 is a possible therapeutic target for severe corticosteroid‐resistant asthma with airway eosinophilia and persistent Th2‐type inflammation, and that ruxolitinib has potential as an alternative pharmacotherapy.

Enhanced airway hyperresponsiveness in asthmatic children and mice with A(H1N1)pdm09 infection

BACKGROUND

Severe asthma exacerbation is an important comorbidity of the 2009 HIN1 pandemic (A(H1N1)pdm09) in asthmatic patients. However, the mechanisms underlying severe asthma exacerbation remain unknown. In this study, airway hyperresponsiveness (AHR) was measured in pediatric asthma patients infected with A(H1N1)pdm09. We also evaluated AHR in asthmatic mice with A(H1N1)pdm09 infection and those with seasonal influenza for comparison.

METHODS

AHRs in asthmatic children were defined as the provocative acetylcholine concentration causing a 20% reduction in forced expiratory volume in 1 s (PC₂₀ ). To investigate the pathophysiology using animal models, BALB/c mice aged 6-8 weeks were sensitized and challenged with ovalbumin. Either mouse-adapted A(H1N1)pdm09, seasonal H1N1 virus (1 × 10⁵ pfu/20 μl), or mock treatment as a control was administered intranasally. At 3, 7, and 10 days after infection, each group of mice was evaluated for AHR by methacholine challenge using an animal ventilator, flexiVent. Lung samples were resected and observed using light microscopy to assess the degree of airway inflammation.

RESULTS

AHRs in the children with bronchial asthma were temporarily increased, and alleviated by 3 months after discharge. AHR was significantly enhanced in A(H1N1)pdm09-infected asthmatic mice compared to that in seasonal H1N1-infected mice (p < .001), peaking at 7 days postinfection and then becoming similar to control levels by 10 days postinfection. Histopathological examination of lung tissues showed more intense infiltration of inflammatory cells and severe tissue destruction in A(H1N1)pdm09-infected mice at 7 days postinfection than at 10 days postinfection.

CONCLUSION

Our results suggest that enhanced AHR could contribute to severe exacerbation in human asthmatic patients with A(H1N1)pdm09 infection.

Clinical features and radiographic findings in cats with eosinophilic, neutrophilic, and mixed airway inflammation (2011-2018)

Background

Idiopathic inflammatory airway disease (IAD) in cats often is described as asthmatic (eosinophilic) or bronchitic (neutrophilic), but this designation requires collection of airway fluid and it fails to consider cats with mixed airway inflammation.

Objective

To identify clinical features that would differentiate inflammatory disease types.

Animals

Forty‐nine cats with nonspecific airway inflammation identified by bronchoscopic bronchoalveolar lavage (BAL) between 2011 and 2018 were evaluated.

Methods

This is a retrospective study. Cats were categorized by BAL differential cytology as having eosinophilic (eosinophils >20% with neutrophils <14%, or eosinophils >50%), mixed (eosinophils 20%‐50% and neutrophils >14% or discordant inflammation from 2 BAL sites), or neutrophilic (neutrophils >14% and eosinophils <20%) inflammation. Type and duration of presenting complaints, signalment, body condition score, respiratory rate, CBC results, bronchoscopy, BAL results (% recovery, total nucleated cell count, differential cell count), and radiographic findings were compared among groups.

Results

Idiopathic IAD was diagnosed in 49 cats, with BAL eosinophilic inflammation in 23, mixed inflammation in 14, and neutrophilic inflammation in 12. Cough was the predominant presenting complaint with no difference in duration of signs among groups (median, 5.5 months). Respiratory rate and effort also did not differ. Cats with eosinophilic inflammation were significantly younger (4.4 ± 3.3 years) than those with neutrophilic (8.0 ±5.6 years) or mixed inflammation (7.5 ± 4.0 years; P = .03). Results of CBC and interpretation of radiographic findings did not differ among groups.

Conclusions and Clinical Importance

Substantial overlap exists in clinical and radiographic findings in cats with various forms of idiopathic airway inflammation.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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