Infections and their role in childhood asthma inception

Preventive effects of prenatal administration of OM-85/BV on asthma and respiratory infection risk in the offspring: A review of animal models

Asthma is the most common chronic disease in childhood affecting the daily lives of many patients despite current treatment regimens. Therefore, the need for new therapeutic approaches is evident, where a primary prevention strategy is the ultimate goal. Studies of children born to mothers in farming environments have shown a lower risk of respiratory infections and asthma development. Already at birth, these newborns have demonstrated accelerated maturation and upregulation of host defense immune functions suggesting a prenatal transplacental training of the innate immune system through maternal microbial exposure. This mechanism could possibly be utilized to help prevent both respiratory infections and asthma in young children. Human studies exploring the potential preventative effects of pregnancy bacterial lysate treatment on asthma and respiratory infections are lacking, however, this has been studied in experimental studies using mice through administrations of the bacterial lysate OM-85. This review will present the current literature on the immunomodulatory effects relevant for respiratory infections and asthma in the offspring of mice treated with OM-85 throughout pregnancy. Further, the review will discuss the cellular and molecular mechanisms behind these effects. In conclusion, we found promising results of an accelerated immune competence and improved resistance to airway challenges as a result of prenatal bacterial lysate treatment that may pave the way for implementing this in human trials to prevent asthma and respiratory infections.

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.

Six Weeks of Supplementation with Bovine Colostrum Effectively Reduces URTIs Symptoms Frequency and Gravity for Up to 20 Weeks in Pre-School Children

Bovine colostrum is considered to provide anti-infective protection. Here, we present the first randomized controlled trial (RCT) aimed at assessing the preventive use of colostrum against upper respiratory tract infections (URTIs) in healthy pre-school children. We analyzed 57 children-35 in the colostrum (COL-dried bovine colostrum) and 22 in the placebo (PBO-dried whey) group, who received these substances as follows: first 15 days 2 × 500 mg and then 30 days 1 × 500 mg. The reporting on the children's health status, specifically on the frequency and gravity of URTI symptoms and abdominal side effects, was performed via an online survey. The influence of colostrum on the frequency of days with URTI symptoms remained significant until the 20th week of observation and reached 31% of median reduction. The median reduction reached 37% when the gravity of symptoms was analyzed. When we grouped symptomatic days into episodes of second gravity level, the reduction in their frequency was even larger (50%) and lasted until the end of the trial (21 weeks). No significant side effects, especially abdominal, were reported during the trial. Colostrum supplementation in pre-school children is well tolerated, safe and provides protection from frequency of URTIs and their gravity.

Reduced Steroid Metabolites Identify Infection-Prone Children in Two Independent Pre-Birth Cohorts

Recurrent respiratory infections are a leading cause of morbidity and mortality in early life, but there is no broadly accepted means to identify infection-prone children during this highly vulnerable period. In this study, we investigated associations between steroid metabolites and incident respiratory infections in two pre-birth cohorts to identify novel metabolomic signatures of early infection proneness. Children from the Vitamin D Antenatal Asthma Reduction Trial and the Copenhagen Prospective Studies on Asthma in Childhood were included, and profiling was performed on plasma samples collected at ages 1 and 6 years. Both cohorts recorded incidence of lower respiratory infections, upper respiratory infections, ear infections, and colds. Poisson regression analysis assessed the associations between 18 steroid metabolites and the total number of respiratory infections that occurred in offspring during follow-up. We found that steroid metabolites across androgenic, corticosteroid, pregnenolone, and progestin classes were reduced in children that suffered more infections, and these patterns persisted at age 6 years, generally reflecting consistency in direction of effect and significance. Our analysis suggested steroid metabolite measurement may be useful in screening for infection proneness during this critical developmental period. Future studies should clinically evaluate their potential utility as a clinical screening tool.

Pediatric thalassemic patients have higher incidence of asthma: A nationwide population-based retrospective cohort study

Introduction

Patients with hemoglobinopathies have been reported to have higher rates of pulmonary complications. Few studies have investigated the association between thalassemia and asthma in children.

Methods

We used the data of one million individuals randomly selected from the Registry for Beneficiaries of the National Health Insurance Research Database. One thalassemic child was matched with four control children without thalassemia according to sex, birth year, birth season, prematurity, and previous enteroviral infection.

Results

A total of 800 hundred thalassemic children and 3200 controls were included. Children with thalassemia had higher rates of developing asthma (41.81 vs 25.70 per 1000 person-years, P < 0.001) than the non-thalassemia controls with an adjusted hazard ratio of 1.37 (95% confidence interval [CI] = 1.19–1.58). Boys in the thalassemia cohort had a significantly higher adjusted incidence hazard ratio (IRR) of asthma than those in the non-thalassemia cohort (adjusted IRR = 1.45, 95% CI = 1.02–1.73). The risk of atopic and nonatopic asthma was higher in the thalassemia cohort than in the non-thalassemia cohort (IRR = 1.3, 1.61, respectively).

Conclusions

Children with thalassemia were more likely to develop asthma. More attention should be paid to the early diagnosis of asthma and prevention of asthma attacks.

The effect of diet in infancy on asthma in young adults: the Merthyr Allergy Prevention Study

INTRODUCTION

Early infant diet might influence the risk of subsequent allergic disease.

METHODS

The Merthyr Allergy Prevention Study (MAPS) was a randomised controlled trial in infants at high risk of allergic disease. The trial determined whether a cow's milk exclusion diet for the first 4 months of life decreased the risk of allergic disease including asthma compared with a normal diet. A soya milk preparation was offered to those in the intervention group. A standardised questionnaire for allergic disease was completed at ages 1, 7, 15 and 23 years, with clinical assessment at 1, 7 and 23 years. The effect of the intervention on the risk of atopy, asthma and wheeze at age 23 years was determined.

FINDINGS

487 subjects entered the study; at age 23 years 299 completed the questionnaire, of which 119 attended clinical assessment. Subjects randomised to the intervention group had a significantly increased risk of atopy (adjusted OR 2.97, 95% CI 1.30 to 6.80; p=0.01) and asthma (OR 2.07, 95%CI 1.09 to 3.91; p=0.03) at age 23 years, but not wheeze (OR 1.43, 95%CI 0.87 to 2.37; p=0.16). Earlier exposure to cow's milk was associated with a decreased risk of wheeze and asthma at age 23 years, while earlier exposure to soya milk was associated with an increased risk of atopy and asthma.

INTERPRETATION

In infants at high risk of allergic disease, either cow's milk exclusion or early soya milk introduction for the first 4 months of life increases the risk of atopy, wheeze and asthma in adulthood.

Mycoplasma pneumoniae infection and risk of childhood asthma: A systematic review and meta-analysis

The etiology of childhood asthma is multifactorial, atypical bacterial pathogens, including Mycoplasma pneumoniae, have been proposed as possible risk factors or contributors. This review aims to assess the possible association between M. pneumoniae infection and childhood asthma. We searched major international literature databases (up to January 10, 2021) to identify relevant studies. We used a random-effects meta-analysis (REM) model to generate the pooled odds ratio (OR) and 95% confidence intervals (CIs). Several subgroups analyses were performed concerning the IgG, IgM, and DNA detection of M. pneumoniae infection. We included 22 eligible studies; these studies involved a total of 5064 children. We found that there was a statistically significant association between M. pneumoniae infection, as determined by IgM serology (OR, 3.13; 95% CI, 1.78-5.48), and DNA detection (OR, 1.57; 95% CI, 1.25-1.97) with increased risk of any type of childhood asthma. Moreover, children with acute asthma had significantly higher seropositivity for anti- M. pneumoniae IgM antibodies (OR, 4.43; 95% CI, 2.80-7.02) than children with stable asthma. Although our findings indicate a positive association between M. pneumoniae infection and childhood asthma, well-designed and -controlled studies are need in the future to rigorously test this association and identify the underlying mechanisms.

Seasonal and monthly variation in peak expiratory flow rate in children with asthma

Background

Although understanding the seasonal patterns of asthma deterioration is important to prevent asthma exacerbation, previous approaches have limitations in evaluating the actual trend of asthma exacerbation.

Objective

This study aimed to evaluate the seasonal and monthly variations in the peak expiratory flow rate (PEFR) among children with asthma.

Methods

A total of 89 patients with asthma were enrolled between December 2012 and March 2015. The PEFR in the morning and evening was recorded daily, and the percentage change in PEFR from baseline was calculated. Generalized estimating equation models were constructed after adjusting for age, sex, body mass index, and sensitization to house dust mites or pollen.

Results

The PEFR records of 11,222 person-days showed a significant decrease in the morning and evening in autumn than in winter by -1.9% (95% confidence interval [CI], -3.73 to -0.15) and -2.1% (95% CI, -3.80 to -0.37), respectively. The morning PEFR was significantly lower in April, August, October, and December than in January with changes of -4.2% (95% CI, -7.08 to -1.23) in April, -3.1% (95% CI, -5.79 to -0.47) in August, -3.7% (95% CI, -6.09 to -1.21) in October, and -1.9% (95% CI, -3.62 to -0.12) in December. The percentage change of evening PEFR significantly decreased by -3.3% (95% CI, -6.38 to -0.25) in April and by -3.3% (95% CI, -5.56 to -1.07) in October.

Conclusion

The PEFR in children with asthma was lower in autumn than in winter. In terms of monthly patterns, the PEFR was significantly reduced in April and October than in January. These results can serve as a basis for preventing asthma exacerbations by developing seasonal or monthly management strategies for children with asthma.

Do Children With Constipation Have Increased Risk of Asthma? Real-World Data From a Nationwide Population-Based Cohort Study

Background: Asthma is one of the most burdensome childhood disorders. Growing evidence disclose intestinal dysbiosis may contribute to asthma via the gut-lung axis. Constipation can lead to alteration of the gut microbiota. The clinical impact of constipation on asthma has not been researched. Therefore, we aim to assess whether pediatric constipation influence the risk of developing asthma by a nationwide population-based cohort study. Methods: We analyzed 10,363 constipated patients and 10,363 individuals without constipation between 1999 and 2013 from Taiwan's National Health Insurance Research Database. Analysis of propensity score was utilized to match age, sex, comorbidities, and medications at a ratio of 1:1. In addition, multiple Cox regression analysis was performed to evaluate the adjusted hazard ratio of asthma. Furthermore, sensitivity tests and a stratified analysis were performed. Results: After adjustment for age, sex, comorbidities, and medications, constipated patients had a 2.36-fold greater risk of asthma compared to those without constipation [adjusted hazard ratio (aHR): 2.36, 95% C.I. 2.04-2.73, p < 0.001]. Furthermore, the severity of constipation is associated with an increased risk of asthma; the adjusted hazard ratio was 2.25, 2.85, and 3.44 within < 3, 3-12, and ≥12 times of laxatives prescription within 1 year, respectively (p < 0.001). Conclusion: Constipation was correlated with a significantly increased risk of asthma. Pediatricians should be aware of the possibility of asthma in constipated patients. Further research is warranted to investigate the possible pathological mechanisms of this association.

Otolaryngologic Management of Chronic Cough in School-aged Children: A Review

Importance

The causes of pediatric chronic cough are numerous and span across several medical subspecialties. In addition to the vast array of underlying causes, there are also several different ways to approach and evaluate chronic cough. Given the frequency with which children present to otolaryngology clinics with this problem, a review of common otolaryngologic causes and an algorithm for evaluation and treatment can be beneficial.

Observations

The primary 3 causes of pediatric chronic cough presenting to an otolaryngologist include infectious causes, reflux, and airway hyperreactivity. In these cases and other instances of specific cough, treatment should be directed at the underlying cause-which may include supportive care, antibiotics, antireflux medication, bronchodilators, inhaled steroids, or other intervention. Patients with nonspecific cough should be treated according to pediatric-specific cough algorithms.

Conclusions and Relevance

Appropriate workup and treatment of chronic cough can lead to higher cure rates, shorter cough duration, and improved quality of life for both patients and caregivers. A systematic approach using cough algorithms can help otolaryngologists effectively manage this common yet complex problem.

Viral infections and wheezing-asthma inception in childhood: is there a role for immunomodulation by oral bacterial lysates?

Severe and recurrent infections of the respiratory tract in early childhood constitute major risk factors for the development of bronchial hyper-responsiveness and obstructive respiratory diseases in later life. In the first years of life, the vast majority of respiratory tract infections (RTI) leading to wheezing and asthma are of a viral origin and severity and recurrence are the consequence of a greater exposure to infectious agents in a period when the immune system is still relatively immature. Therefore, boosting the efficiency of the host immune response against viral infections seems to be a rational preventative approach. In the last decades it has been demonstrated that living in farm environments, i.e. early-life exposure to microbes, may reduce the risk of allergic and infectious disorders, increasing the immune response efficacy. These findings have suggested that treatment with bacterial lysates could promote a nonspecific immunomodulation useful in the prevention of recurrent RTIs and of wheezing inception and persistence. Experimental and clinical studies showing the reduction of RTI frequency and severity in childhood and elucidating the involved mechanisms can support this hypothesis.

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.

Exposure to Ascaris lumbricoides infection and risk of childhood asthma in north of Iran

BACKGROUND

Asthma and Ascaris lumbricoides infection are common health issues affecting 250 and 700 million people worldwide, respectively. The relationship between ascariasis and asthma is a matter of substantial interest and research.

METHODS

We performed a case-control study to evaluate whether the exposure to Ascaris infection is associated with asthma in children. We also assessed potential risk factors for Ascaris infection and asthma in study area. We enrolled 145 asthmatic children and 115 healthy controls. The Global Initiative for Asthma guideline was used to evaluate asthma symptoms and severity in study participants. Ascaris infection was assessed by the presence of anti-Ascaris IgG ≥ 11 IU/mL measured by enzyme-linked immunosorbent assay.

RESULTS

We have found a significant relationship between exposure to Ascaris and asthma (odds ratio, 2.92; 95% CI 1.04-8.18; P value = 0.034), and this relationship remained significant after adjustment for covariates (adjusted OR, 3.36; 95% CI 1.04-13%; P value = 0.047). Ascaris infection was more frequent in children with mild sustainable asthma (13.2%; 15/113) than in children with moderate sustainable asthma (6.2%, 2/32), although there was a non-significant difference between these groups (OR, 2.3; 95% CI 0.5-10.1; P value = 0.35). Based on results of a multi-regression analysis, contact with soil (OR, 6.7; 95% CI 1.9-23.5), and drinking unsafe water (OR, 4.2; 95% CI 1.2-14.2) were significant risk factors for Ascaris infection in the study area.

CONCLUSION

Results of this study suggest that A. lumbricoides infection might affect susceptibility to asthma in children. These results could be useful in prevention, early diagnosis and management of childhood asthma.

A review on the pathophysiology of asthma remission

Asthma is a chronic respiratory condition, which is highly prevalent worldwide. Although no cure is currently available, it is well recognized that some asthma patients can spontaneously enter remission of the disease later in life. Asthma remission is characterized by absence of symptoms and lack of asthma-medication use. Subjects in asthma remission can be divided into two groups: those in clinical remission and those in complete remission. In clinical asthma remission, subjects still have a degree of lung functional impairment or bronchial hyperresponsiveness, while in complete asthma remission, these features are no longer present. Over longer periods, the latter group is less likely to relapse. This remission group is of great scientific interest due to the higher potential to find biomarkers or biological pathways that elicit or are associated with asthma remission. Despite the fact that the definition of asthma remission varies between studies, some factors are reproducibly observed to be associated with remitted asthma. Among these are lower levels of inflammatory markers, which are lowest in complete remission. Additionally, in both groups some degree of airway remodeling is present. Still, the pathological disease state of asthma remission has been poorly investigated. Future research should focus on at least two aspects: further characterisation of the small airways and airway walls in order to determine histologically true remission, and more thorough biological pathway analyses to explore triggers that elicit this phenomenon. Ultimately, this will result in pharmacological targets that provide the potential to steer the course of asthma towards remission.

Respiratory Viruses and Treatment Failure in Children With Asthma Exacerbation

: media-1vid110.1542/5771275574001PEDS-VA_2017-4105Video Abstract OBJECTIVES: Respiratory pathogens commonly trigger pediatric asthma exacerbations, but their impact on severity and treatment response remains unclear.

METHODS

We performed a secondary analysis of the Determinants of Oral Corticosteroid Responsiveness in Wheezing Asthmatic Youth (DOORWAY) study, a prospective cohort study of children (aged 1-17 years) presenting to the emergency department with moderate or severe exacerbations. Nasopharyngeal specimens were analyzed by RT-PCR for 27 respiratory pathogens. We investigated the association between pathogens and both exacerbation severity (assessed with the Pediatric Respiratory Assessment Measure) and treatment failure (hospital admission, emergency department stay >8 hours, or relapse) of a standardized severity-specific treatment. Logistic multivariate regressions were used to estimate average marginal effects (absolute risks and risk differences [RD]).

RESULTS

Of 958 participants, 61.7% were positive for ≥1 pathogen (rhinovirus was the most prevalent [29.4%]) and 16.9% experienced treatment failure. The presence of any pathogen was not associated with higher baseline severity but with a higher risk of treatment failure (20.7% vs 12.5%; RD = 8.2% [95% confidence interval: 3.3% to 13.1%]) compared to the absence of a pathogen. Nonrhinovirus pathogens were associated with an increased absolute risk (RD) of treatment failure by 13.1% (95% confidence interval: 6.4% to 19.8%), specifically, by 8.8% for respiratory syncytial virus, 24.9% for influenza, and 34.1% for parainfluenza.

CONCLUSIONS

Although respiratory pathogens were not associated with higher severity on presentation, they were associated with increased treatment failure risk, particularly in the presence of respiratory syncytial virus, influenza, and parainfluenza. This supports influenza prevention in asthmatic children, consideration of pathogen identification on presentation, and exploration of treatment intensification for infected patients at higher risk of treatment failure.

Influenza burden, prevention, and treatment in asthma-A scoping review by the EAACI Influenza in asthma task force

To address uncertainties in the prevention and management of influenza in people with asthma, we performed a scoping review of the published literature on influenza burden; current vaccine recommendations; vaccination coverage; immunogenicity, efficacy, effectiveness, and safety of influenza vaccines; and the benefits of antiviral drugs in people with asthma. We found significant variation in the reported rates of influenza detection in individuals with acute asthma exacerbations making it unclear to what degree influenza causes exacerbations of underlying asthma. The strongest evidence of an association was seen in studies of children. Countries in the European Union currently recommend influenza vaccination of adults with asthma; however, coverage varied between regions. Coverage was lower among children with asthma. Limited data suggest that good seroprotection and seroconversion can be achieved in both children and adults with asthma and that vaccination confers a degree of protection against influenza illness and asthma-related morbidity to children with asthma. There were insufficient data to determine efficacy in adults. Overall, influenza vaccines appeared to be safe for people with asthma. We identify knowledge gaps and make recommendations on future research needs in relation to influenza in patients with asthma.

Toxocara spp. infection and risk of childhood asthma: A systematic review and meta-analysis

Asthma is one of the most common chronic respiratory disease worldwide, with a negative impact on quality of life and socio-economic status of patients. There are some evidences to suggest that Toxocara infection is a neglected risk factor for childhood asthma. We performed a systematic review and meta-analysis to further understanding of this relationship. Five databases include PubMed, Science Direct, Scopus, Web of Science (ISI), and Google scholar were searched (up to October 2017) to identify the relevant studies. We used random-effects meta-analysis model to estimate the pooled odds ratio (OR) and 95% confidence intervals (CI). Heterogeneity was assessed with the Q-test and I² statistic. A total of 17 studies including 11 studies with case-control design (1139 patients and 1023 controls) and six studies with cross-sectional design (a total of 5469 participants, 872 asthmatics, and 4597 non-asthmatics children) met the eligibility criteria. An increased risk for asthma was observed in children with Toxocara infection seropositivity (OR, 1.91; 95% CI, 1.47-2.47). In sub-group analysis, the pooled ORs were (OR, 2.13; 95% CI, 1.43-3.15) and (OR, 1.73; 95% CI, 1.23-2.44) for case-control and cross-sectional studies, respectively. Moreover, considering to specific IgE seropositivity, a pooled OR of 2.36 (95% CI, 0.93-5.98) was observed. In conclusion, this meta-analysis revealed that children infected with Toxocara spp. are more likely to have asthma compared to non-infected children. More studies (especially longitudinal studies) are needed to further investigate the impact of Toxocara spp. infection on the onset or development of asthma.

Asthma and allergic rhinitis in childhood: what's new

Novel approaches are currently offered for the diagnostic workup and therapeutic management of allergic rhinitis and asthma. New predictive biomarkers of allergy and asthma are available. Primary and secondary prevention, earlier intervention, and modification of the natural history of allergic rhinitis and asthma are being intensively investigated. This review highlights advances in the understanding of the etiology, diagnosis, and management of atopic airway diseases in childhood, as well as prenatal and early-life risk factors and strategies for prevention.

Prevalence of asthma symptoms in Golestan schoolchildren aged 6-7 and 13-14 years in Northeast Iran

Asthma is the most common chronic disease among children, and its incidences are often imminent among elementary schoolchildren. This study aimed to examine the prevalence of asthma symptoms in Golestan schoolchildren aged 6-7 and 13-14 years in Northeast Iran. The prevalence rate was compared according to age group (aged 6-7 years vs. aged 13-14 years) and gender (male vs. female). In this cross-sectional study, 1706 Iranian schoolchildren aged 6-7 and 13-14 years in Golestan Province were enrolled. Participants completed questionnaires between February and July 2014. Asthma symptoms were assessed using the questionnaire of the International Study of Asthma and Allergies in Childhood protocol in Persian. The logistic regression model was used to estimate the odds ratios (ORs) and 95% confidence intervals (CIs) of the asthma symptoms for each of the gender and age groups. The prevalence rates of "current asthma" symptoms and "asthma ever" in all the children were estimated as 9.5% and 7.5%, respectively. The prevalence of asthma ("asthma ever" and "wheezing in the past 12 months") in junior high schoolchildren (aged 13-14 years) is higher than that in elementary schoolchildren (aged 6-7 years) (P < 0.05). The prevalence of the severity of wheezing in girls is lower than that in boys (OR = 1.7, 95%CI = 1.06-2.96, P = 0.02). Asthma is still a major public health problem. This study shows that the prevalence of the asthma symptoms in boys is lower than that in girls in both age groups, and the severity of asthma in girls is higher than that in boys aged 13-14 years.

Acute asthma, prognosis, and treatment

Asthma affects about 300 million people globally and accounts for 1 in every 250 deaths in the world. Approximately 12 million people in the United States each year experience an acute exacerbation of their asthma, a quarter of which require hospitalization. Acute asthma should be differentiated from poor asthma control. Patients with acute asthma will exhibit increasing shortness of breath, chest tightness, coughing, and/or wheezing. In contrast, poor asthma control typically presents with a diurnal variability in airflow and is a characteristic that is usually not seen during an acute exacerbation. The history should include a review of comorbidities, adherence to medications, previous episodes of near-fatal asthma, and whether the patient has experienced multiple emergency department visits or hospitalizations, particularly those requiring admission to an intensive care unit involving respiratory failure, intubation, and mechanical ventilation. Patient education is important to ensure that the patient understands that asthma is mostly a chronic disease and necessitates the avoidance of allergens, prevention of infections, adherence with routine vaccinations, management of comorbid conditions, and adherence to treatment regimens. This article is a structured review of the available literature regarding the diagnosis and management of acute asthma.

[Airway inflammation induced by Poly(I:C) stimulation in the late stage of respiratory syncytial virus infection in mice and its mechanism]

OBJECTIVE

To investigate the pathogenic mechanisms of airway inflammation and recurrent wheezing induced by recurrent respiratory virus infection after respiratory syncytial virus (RSV) infection.

METHODS

Sixty-four female BALB/c mice (aged 6-8 weeks) were randomly divided into four groups: control, RSV, Poly(I:C), and RSV+Poly(I:C) (n=16 each). The bronchoalveolar lavage fluid (BALF) was collected on the 3rd day after Poly(I:C) administration, and the total cell number and differential counts in BALF were determined. Hematoxylin-eosin staining was used to observe pulmonary pathological changes. The airway responsiveness was detected. ELISA was used to measure the levels of interferon-γ (IFN-γ), interleukin-4 (IL-4), interleukin-13 (IL-13), matrix metallopeptidase-9 (MMP-9), and tissue inhibitor of metalloproteinase-1 (TIMP-1) in BALF.

RESULTS

Compared with the other three groups, the RSV+Poly(I:C) group had significant increases in the total number of inflammatory infiltrating cells in the airway, airway responsiveness, and MMP-9 level in BALF (P<0.05). The RSV+Poly(I:C) group showed more severe pulmonary tissue injuries compared with the control and RSV groups (P<0.01). Compared with the RSV group, the RSV+Poly(I:C) group showed significant reductions in the levels of IL-4 and TIMP-1 in BALF (P<0.01).

CONCLUSIONS

Viral re-infection in the late stage of RSV infection may cause an imbalance of MMP-9/TIMP-1 expression and thus contribute to aggravated airway inflammation.

Factors associated with the time to the first wheezing episode in infants: a cross-sectional study from the International Study of Wheezing in Infants (EISL)

Male gender, asthmatic heredity, perinatal tobacco smoke exposure and respiratory infections have been associated with wheeze in the first years of life, among other risk factors. However, information about what factors modify the time to the first episode of wheeze in infants is lacking. The present study analyses which factors are associated with shorter time to the first episode of wheeze in infants. Parents of 11- to 24-month-old children were surveyed when attending their health-care centres for a control visit. They answered a questionnaire including the age in months when a first wheeze episode (if any) had occurred (outcome variable). The study was performed in 14 centres in Latin America (LA) and in 8 centres in Europe (EU) (at least 1,000 infants per centre). Factors known to be associated with wheezing in the cohort were included in a survival analysis (Cox proportional hazards model). Summary hazard ratios adjusted for all risk factors (aHR) were calculated using the meta-analysis approach with random effects. A total of 15,067 infants had experienced wheezing at least once, out of 35,049 surveyed. Male gender in LA (aHR 1.05, 95% confidence interval (CI) 1.00-1.10, P=0.047), parental asthma in LA and EU (aHR 1.05, 95% CI 1.00-1.11, P=0.037), infant eczema in EU (aHR 1.25, 95% CI 1.12-1.39, P<0.001) and having a cold during the first 3 months in LA and EU (aHR 1.97, 95% CI 1.90-2.04, P<0.001), in LA (aHR 1.98, 95% CI 1.90-2.06, P<0.001) and in EU (aHR 1.91, 95% CI 1.75-2.09, P<0.001) were associated with a shorter period of time to the first episode. Breast feeding for at least 3 months was associated with a longer period, only in LA (aHR 0.91, 95% CI 0.86-0.96, P<0.001). Cold symptoms during the first 3 months is the most consistent factor shortening the time to the first episode of wheezing; breast feeding for ⩾3 months delays it only in LA, whereas eczema shortens it only in EU. Avoiding a common cold in the first months of life could be a good strategy to delay the first wheeze episode; however, cohort studies will help to elucidate this association.

Respiratory allergies in childhood: Recent advances and future challenges

The burden of allergic airway diseases still represents a major health problem in childhood. Despite many different options are currently available for the diagnostic work-up and management, the overall disease control in terms of impact on quality of life, morbidity and mortality, is not yet satisfactory. The extreme variability of individual risk factors and severity determinants may account for it. On the other side, the knowledge of the multifaceted allergy background could pave the way to primary prevention, early intervention and disease course modification. In fact, most of current research is focusing on the identification of biological and clinical predictive markers of allergy and asthma onset. This review aims at summarizing the latest achievements concerning the complex inter-relation between genetic predisposition and environmental factors, and their impact on prevention strategies and early identification of at risk subjects. An update on the diagnostic and monitoring tools as well as an insight into the newest treatments options is also provided.

TLR3 activation increases chemokine expression in human fetal airway smooth muscle cells

Viral infections, such as respiratory syncytial virus and rhinovirus, adversely affect neonatal and pediatric populations, resulting in significant lung morbidity, including acute asthma exacerbation. Studies in adults have demonstrated that human airway smooth muscle (ASM) cells modulate inflammation through their ability to secrete inflammatory cytokines and chemokines. The role of ASM in the developing airway during infection remains undefined. In our study, we used human fetal ASM cells as an in vitro model to examine the effect of Toll-like receptor (TLR) agonists on chemokine secretion. We found that fetal ASM express multiple TLRs, including TLR3 and TLR4, which are implicated in the pathogenesis of respiratory syncytial virus and rhinovirus infection. Cells were treated with TLR agonists, polyinosinic-polycytidylic acid [poly(I:C)] (TLR3 agonist), lipopolysaccharide (TLR4 agonist), or R848 (TLR7/8 agonist), and IL-8 and chemokine (C-C motif) ligand 5 (CCL5) secretion were evaluated. Interestingly, poly(I:C), but neither lipopolysaccharide nor R848, increased IL-8 and chemokine (C-C motif) ligand 5 secretion. Examination of signaling pathways suggested that the poly(I:C) effects in fetal ASM involve TLR and ERK signaling, in addition to another major inflammatory pathway, NF-κB. Moreover, there are variations between fetal and adult ASM with respect to poly(I:C) effects on signaling pathways. Pharmacological inhibition suggested that ERK pathways mediate poly(I:C) effects. Overall, our data show that poly(I:C) initiates activation of proinflammatory pathways in developing ASM, which may contribute to immune responses to infection and exacerbation of asthma.

Neutrophils in respiratory syncytial virus infection: A target for asthma prevention

Lower respiratory tract infections by respiratory syncytial virus (RSV) are the foremost cause of infant hospitalization and are implicated in lasting pulmonary impairment and the development of asthma. Neutrophils infiltrate the airways of pediatric patients with RSV-induced bronchiolitis in vast numbers: approximately 80% of infiltrated cells are neutrophils. However, why neutrophils are recruited to the site of viral respiratory tract infection is not clear. In this review we discuss the beneficial and pathologic contributions of neutrophils to the immune response against RSV infection. Neutrophils can limit viral replication and spread, as well as stimulate an effective antiviral adaptive immune response. However, low specificity of neutrophil antimicrobial armaments allows for collateral tissue damage. Neutrophil-induced injury to the airways during the delicate period of infant lung development has lasting adverse consequences for pulmonary architecture and might promote the onset of asthma in susceptible subjects. We suggest that pharmacologic modulation of neutrophils should be explored as a viable future therapy for severe RSV-induced bronchiolitis and thereby prevent the inception of subsequent asthma. The antiviral functions of neutrophils suggest that targeting of neutrophils in patients with RSV-induced bronchiolitis is best performed under the umbrella of antiviral treatment.

Infection-related asthma

The role of infection in asthma is varied in that it may exacerbate established asthma or contribute to the initial development of the clinical onset of asthma. Mounting evidence implicates both roles with particular viral pathogens, namely human rhinovirus and respiratory syncytial virus, among the most likely culprits in asthma inception. Once asthma is present, infection, particularly viral infection, is a common precipitant of asthma exacerbations. Bacterial infections and colonization also have been associated with exacerbation and recurrent wheeze, an effect that may be independent or a cofactor with viruses. Atypical bacterial infections such as Mycoplasma pneumoniae and Chlamydia pneumoniae and fungi in the case of allergic bronchopulmonary aspergillosis, also play a potential role in inducing and exacerbating this disease. In addition, certain individuals may have a genetic predisposition toward viral-induced wheezing and the development of asthma. This article will discuss host and environmental factors, common pathogens, clinical characteristic, and genetic influences associated with infection-related asthma.

Early life environmental predictors of asthma age-of-onset

Prevention strategies that delay the onset of asthma may improve clinical outcomes. To identify early life environmental exposures associated with asthma age-of-onset and potential genetic modifiers of these exposures, we studied 1085 subjects with physician-diagnosed asthma and disease onset at or after age two. Subjects reported retrospectively on their exposure to 17 environmental factors before the age of two. The presence of individual or combinations of these early life exposures was then tested for association with variation in asthma age-of-onset. For exposures significantly associated with age-of-onset, we tested if 26 single nucleotide polymorphisms (SNP) with an established association with allergic disease significantly modified the effect of the exposure. Five environmental exposures were significantly associated with variation in asthma age-of-onset after correction for multiple testing: carpet at home (P = 6 × 10⁻⁵), a serious chest illness (P = 10⁻⁴), father a cigarette smoker (P = 6 × 10⁻⁴) and direct exposure to father's smoking (P = 3 × 10⁻⁴). Individuals with early childhood asthma onset, between the ages of two and six, were 1.4-fold (CI 1.1–1.9) more likely to report having lived in a house with carpet and 2.1-fold (CI 1.3–3.5) more likely to report suffering a serious chest illness before the age of two, than asthmatics with later disease onset. We further found these individual risks to increase to 3.2-fold (CI 1.7–6.0) if carpet exposure and suffering a serious chest illness co-occurred before age two. Paternal smoking exposures were less likely to be reported by asthmatics with early when compared to later disease onset (OR 0.5, CI 0.3–0.7). There were no significant SNP interactions with these environmental exposures after correction for multiple testing. Our results suggest that disease onset in individuals at a high-risk of developing asthma can potentially be delayed by avoiding exposure to carpet at home and preventing serious chest illnesses during the first 2 years of life.

Infections and their role in childhood asthma inception

The association of early-onset wheezing with common viral and bacterial infections has raised significant interest in the role of infections in childhood asthma inception. This article serves to review these relationships among infections, host factors, and asthma inception in childhood.