The roles of gut microbiota on the natural course of atopic dermatitis (AD) are not yet fully understood. We investigated whether the composition and function of gut microbiota and short-chain fatty acids (SCFAs) at 6 months of age could affect the natural course of AD up to 24 months in early childhood. Fecal samples from 132 infants were analyzed using pyrosequencing, including 84 healthy controls, 22 transient AD and 26 persistent AD subjects from the Cohort for Childhood Origin of Asthma and Allergic Diseases (COCOA) birth cohort. The functional profile of the gut microbiome was analyzed by whole-metagenome sequencing. SCFAs were measured using gas chromatography-mass spectrometry. Low levels of Streptococcus and high amounts of Akkermansia were evident in transient AD cases, and low Clostridium, Akkermansia and high Streptococcus were found in children with persistent AD. The relative abundance of Streptococcus positively correlated with scoring of AD (SCORAD) score, whereas that of Clostridium negatively correlated with SCORAD score. The persistent AD group showed decreased gut microbial functional genes related to oxidative phosphorylation compared with healthy controls. Butyrate and valerate levels were lower in transient AD infants compared with healthy and persistent AD infants. Compositions, functions and metabolites of the early gut microbiome are related to natural courses of AD in infants.

Kang MJ, et al. Allergy Asthma Immunol Res. 2021 May;13(3):404-419. https://doi.org/10.4168/aair.2021.13.3.404

Lee E, et al. J Korean Med Sci. 2018 Mar;33(16):e119. https://doi.org/10.3346/jkms.2018.33.e119

Kim JH, et al. Allergy Asthma Immunol Res. 2018 Jul;10(4):397-405. https://doi.org/10.4168/aair.2018.10.4.397

Rationale: Exposure to humidifier disinfectants (HDs) can increase the risk of asthma, but the characteristics of HD-related asthma are currently unclear. Polyhexamethylene guanidine (PHMG)–containing HD was the most commonly used and the most frequently associated with HD-associated lung injury. Objectives: To investigate the characteristics of PHMG-induced asthma. Methods: This general population–based birth cohort study used data from the Panel Study of Korean Children from 2008 (n = 846). Spirometry, bronchial provocation tests, detailed history recording, and physical examinations were performed on 7-year-old patients (n = 362). Exploratory analysis of plasma proteomics was performed. Results: Compared with the healthy control group, forced expiratory volume in 1 second was the lowest in PHMG-exposed asthma group (z-score = −0.806; 95% confidence interval, −1.492 to −0.119). The positive rate of bronchial hyperresponsiveness was lower in children with PHMG-exposed asthma compared with children with asthma without HD exposure (13.3% vs. 47.4%). Long-term exposure to low-intensity PHMG before the age of 3 years was associated with asthma symptoms. Periostin was higher in subjects with asthma without HD exposure compared with the healthy control subjects. The inducible T-cell costimulator ligand and hepatocyte growth factor activator were lower in PHMG-exposed asthma compared with asthma without exposure. Hepatocyte growth factor activator had a positive correlation with forced vital capacity (z-score) in asthma with PHMG exposure (r = 0.78; P < 0.01). Conclusions: The asthma associated with low-intensity exposure to PHMG is characterized by lower lung function, lower positive rates of bronchial hyperresponsiveness, and varied distributions of plasma proteins. These findings suggest that asthma related to PHMG exposure may constitute a different mechanism of asthma pathophysiology.