Current Asthma Prevalence Using Methacholine Challenge Test in Korean Children from 2010 to 2014.

BACKGROUND: Most epidemiological studies depend on the subjects' response to asthma symptom questionnaires. Questionnaire-based study for childhood asthma prevalence may overestimate the true prevalence. The aim of this study was to investigate the prevalence of "Current asthma" using the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire and methacholine challenge test in Korean children. METHODS: Our survey on allergic disease included 4,791 children (age 7-12 years) from 2010 to 2014 in Korean elementary schools. Bronchial hyperresponsiveness (BHR) was defined as provocative concentration of methacholine causing a 20% fall in forced expiratory volume in one second (FEV1) (PC20) ≤ 16 mg/mL. "Current asthma symptoms" was defined as positive response to "Wheezing, current," "Treatment, current," or "Exercise, current." "Current asthma" was defined when the subjects with "Current asthma symptoms" showed BHR on the methacholine challenge test or had less than 70% of predicted FEV1 value. RESULTS: The prevalence of "Wheezing, ever," "Wheezing, current," "Diagnosis, ever," "Treatment, current," "Exercise, current," and "Current asthma symptoms" was 19.6%, 6.9%, 10.0%, 3.3%, 3.5%, and 9.6%, respectively, in our cross-sectional study of Korean elementary school students. The prevalence of BHR in elementary school students was 14.5%. The prevalence of BHR in children with "Wheezing, ever," "Wheezing, current," "Diagnosis, ever," "Treatment, current," and "Exercise, current" was 22.3%, 30.5%, 22.4%, 28.8%, and 29.9%, respectively. BHR was 26.1% in those with "Current asthma symptoms." The prevalence of "Current asthma" was 2.7%. CONCLUSIONS: Our large-scale study provides 2.7% prevalence of current asthma in Korean elementary school children. Since approximately one third of the children who have "Current asthma symptoms" present BHR, both subjective and objective methods are required to accurately predict asthma in subjects with asthma symptoms.

Urine Bacteria-Derived Extracellular Vesicles and Allergic Airway Diseases in Children.

BACKGROUND: Microbiota and human allergic airway diseases have been proven to be interrelated. Bacteria-derived extracellular vesicle (EV)s are known to play important roles in interbacterial and human-bacteria communications, but their relationship with allergies has not been examined yet. Urine EVs were investigated to determine whether they could be used as biomarkers for monitoring allergic airway diseases in children. METHODS: Subjects were 4 groups of chronic rhinitis (CR), allergic rhinitis (AR), atopic asthma (AS) and healthy controls. Single voided urine samples were collected. Urine EVs were isolated and their DNA was extracted for 16S-rDNA pyrosequencing. RESULTS: A total of 118 children participated in this study; 27, 39, 19, and 33 were in the CR, AR, AS, and control group, respectively. The AR had a significantly high Chao-1 index than that of controls. Principal component analysis revealed dysbiosis in the CR, AR, and AS compared to the controls. One phylum and 19 families and genera were significantly enriched or depleted in the disease groups compared to the controls; the Actinobacteria phylum and the Sphingomonadaceae family were more abundant in the AS and CR, the Comamonadaceae family, the Propionibacteraceae family, Propionibacterium and Enhydrobacter were more enriched in the CR, and the Methylobacteriaceae family and Methylobacterium were more abundant in each disease group, while the Enterobacteriaceae family was depleted in each disease group. CONCLUSIONS: CR, AR, and AS had a distinct composition of urine EVs. Urine EVs could be an indicator for assessing allergic airway diseases in children.

Moderate to severe atopic dermatitis in children: focus on systemic Th2 cytokine receptor antagonists and Janus kinase inhibitors.

Atopic dermatitis (AD) is a lifelong disease that markedly impairs quality of life. AD is considered a starting point of the "atopic march," which begins at a young age and may progress to systemic allergic diseases. Moreover, it is strongly associated with comorbid allergic and inflammatory diseases including arthritis and inflammatory bowel disease. Understanding the pathogenesis of AD is essential for the development of targeted therapies. Epidermal barrier dysfunction, immune deviation toward a T helper 2 proinflammatory profile, and microbiome dysbiosis play important roles via complex interactions. The systemic involvement of type 2 inflammation, wheather acute or chronic, and whether extrinsic or intrinsic, is evident in any type of AD. Studies on AD endotypes with unique biological mechanisms have been conducted according to clinical phenotypes, such as race or age, but the endotype for each phenotype, or endophenotype, has not yet been clearly identified. Therefore, AD is still being treated according to severity rather than endotype. Infancy-onset and severe AD are known risk factors leading to atopic march. In addition, up to 40% of adult AD are cases of infancy-onset AD that persist into adulthood, and these are often accompanied by other allergic diseases. Therefore, early intervention strategies to identify high-risk infants and young children, repair an impaired skin barrier, and control systemic inflamation may improve long-term outcomes in AD patients. However, to the best of our knowledge, no study has evaluated the effectiveness of early intervention on atopic march using systemic therapy in high-risk infants. This narrative review addresses the latest knowledge of systemic treatment, including Th2 cytokine receptor antagonists and Janus kinase inhibitors, for children with moderate to severe AD that is refractory to topical treatment.

Bacterial Microbiota-derived Extracellular Vesicles in Children With Allergic Airway Diseases: Compositional and Functional Features.

PURPOSE: Bacterial extracellular vesicles (EVs) play crucial roles in bacteria-host interactions. Due to their cargo, EVs are considered fingerprints of the parent cell, which are detectable in body fluids. We studied the composition and function of bacterial microbiota-derived EVs genes in urine to evaluate whether they have specific characteristics concerning allergic airway disease. METHODS: Subjects were from elementary school surveys and classified into 3 groups according to questionnaires and sensitization to aeroallergens: the allergic airway group (AA, n = 16), atopic controls (AC, n = 7) and healthy controls (HC, n = 26). The bacterial EVs were isolated from voided urine samples, their nucleic acid was extracted for 16S ribosomal RNA pyrosequencing and then characterized using α-diversity, ß-diversity, network analysis, intergroup comparison of bacterial composition and predicted functions, and correlation with total immunoglobulin E (IgE), eosinophils% and fractional exhaled NO. RESULTS: The compositional α-diversity was the highest in AA, while functional α-diversity was the highest in HC. AA had a distinct clustering with the least intersample variation. Klebsiella, Haemophilus, members from Lachnospiraceae and Ruminococcaceae, and the pathways of sphingolipid and glycerolipid metabolism, and biosynthesis of peptidoglycan and lysine were the highest in AA and positively correlated with total IgE or eosinophil%. Genetic information processing function contributed to 48% of the intergroup variance and was the highest in AA. Diaphorobacter, Acinetobacter, and the pathways of short-chain fatty acids and anti-oxidants metabolism, lysine and xenobiotic degradation, and lipopolysaccharide biosynthesis were the lowest in AA and negatively correlated with total IgE or eosinophil%. The bacterial composition and function in AC were closer to those in HC. The bacterial network was remarkably dense in HC. CONCLUSIONS: The bacterial microbiota-derived EVs in urine possess characteristic features in allergic airway disease with a remarkable correlation with total IgE and eosinophil%. These findings suggest that they may play important roles in allergic airway diseases.

How Accurate Are the ISAAC Questions for Diagnosis of Allergic Rhinitis in Korean Children?

Background: The aims of this study were to investigate the prevalence of allergic rhinitis (AR) and the accuracy of the International Study of Asthma and Allergies in Childhood (ISAAC) questions for diagnosis of AR, in Korean children. Methods: Students that participated in an allergic disease prevalence survey in 2010⁻2017 were evaluated (n = 18,425) using questionnaires and a skin prick test (SPT). Age-stratified (5-7, 8-10, 11-13, 14-16 years) prevalence of four rhinitis questions, accuracy of the questions for AR, and proportion of comorbidities in the AR and non-AR (NAR) groups were evaluated. Results: The proportion of students responding to the questionnaire that ever had symptoms of AR since birth, that is, the prevalence of "symptom, ever" was 47.6%. Based on the questionnaire and SPT, overall prevalence of AR and NAR were 21% and 26.5%, respectively. The sensitivity, specificity, and accuracy of "symptom, ever" were 57.5%, 58.4%, and 58.1%, respectively, and those of "diagnosis, ever", who had ever been diagnosed with AR, were 39.8%, 76.9%, and 63.4%, respectively. Questionnaire-based asthma, atopic dermatitis, and food allergy were significantly associated with the AR group compared to the NAR group. Conclusions: Since the AR accuracy of the questionnaire is about 60%, it should be considered that the questionnaire based survey overestimates the true prevalence of AR in Korean children.