Combined metagenomic- and culture-based approaches to investigate bacterial strain-level associations with medication-controlled mild-moderate atopic dermatitis.

Background: The skin microbiome is disrupted in atopic dermatitis (AD). Existing research focuses on moderate to severe, unmedicated disease. Objective: We sought to investigate metagenomic- and culture-based bacterial strain-level differences in mild, medicated AD and the effects these have on human keratinocytes (HKs). Methods: Skin swabs from anterior forearms were collected from 20 pediatric participants (11 participants with AD sampled at lesional and nonlesional sites and 9 age- and sex-matched controls). Participants had primarily mild to moderate AD and maintained medication use. Samples were processed for microbial metagenomic sequencing and bacterial isolation. Isolates identified as Staphylococcus aureus were tested for enterotoxin production. HK cultures were treated with cell-free conditioned media from representative Staphylococcus species to measure barrier effects. Results: Metagenomic sequencing identified significant differences in microbiome composition between AD and control groups. Differences were seen at the species and strain levels for Staphylococci, with S aureus found only in participants with AD and differences in Staphylococcus epidermidis strains between control and AD swabs. These strains showed differences in toxin gene presence, which was confirmed in vitro for S aureus enterotoxins. The strain from the participant with the most severe AD produced enterotoxin B levels more than 100-fold higher than the other strains (P < .001). Strains also displayed differential effects on HK metabolism and barrier function. Conclusions: Strain-level differences in toxin genes from Staphylococcus strains may explain varying effects on HK, with S aureus and non-aureus strains negatively affecting viability and barrier function. These differences are likely important in AD pathogenesis.

Development and Dynamic Responsiveness of the Acute Asthma Exacerbation Survey in Patients With Moderate to Severe Disease.

BACKGROUND: The recall periods and response scales of existing surveys of asthma control are poorly suited for studying acute exacerbations. OBJECTIVE: To develop an instrument able to predict exacerbations after the onset of acute symptoms and with a recall window sufficiently short to study recovery. METHODS: We developed the six-item Acute Asthma Exacerbation Survey (AAES). Data were collected at baseline, acute, and recovery visits within an established longitudinal protocol for participants with severe asthma. Participants scheduled acute study visits at the first sign of a cold. Nasal lavage samples and lung function measurements were also collected. The AAES data were analyzed using Cronbach α, Spearman correlations, and Kruskal-Wallace methods. We used logistic regression for predictors of bursts of oral corticosteroids (OCS). RESULTS: Of 130 participants studied at baseline, 52 returned for an acute visit. The AAES scores were elevated at the acute visit and returned to baseline after recovery independently of respiratory virus detection. Cronbach α for the AAES was 0.853, 0.822, and 0.889 at the three respective visits. Compared with participants not needing burst OCS, those with exacerbations had higher acute AAES scores (16 [13.5-18] vs 11.5 [8.2-14], median [interquartile range]; P = .017) and a larger reduction from baseline in lung function. For each 3-point increase in AAES scores, the odds ratio for burst OCS use was 1.64 (95% CI, 1.04-2.57; P = .030). CONCLUSIONS: The AAES is internally consistent and dynamically responsive during acute asthma exacerbations. Additional validation studies are warranted to support future trials and aid in clinical decision-making.

Ensemble Analysis Identifies Nasal 15-Keto-PGE2 as a Predictor of Recovery in Experimental Rhinovirus Colds.

BACKGROUND: Symptom intensity during a common cold is highly variable, particularly after the illness peaks, contributing to delay in recovery. Rhinoviruses frequently cause colds and, during acute infections, generate leukotriene B4 and prostaglandin E2 (PGE2). PGE2 is known to initiate oxylipin class switching and resolution of acute inflammation. Thus, we hypothesized that during acute rhinovirus colds, oxylipins with pro-resolving capabilities reduce symptom severity and speed recovery. METHODS: Four groups of healthy volunteers were inoculated with placebo or 3 different doses of rhinovirus A16. Participants kept daily records of symptoms and contributed serial nasal lavage fluid samples. We collected semi-quantitative mass spectrometry data for 71 oxylipins in these acute samples from all participants. An ensemble analysis approach was used to further reduce this dataset. RESULTS: Levels of 15-keto-PGE2 at day 3 of the cold were consistently among the top candidates in these models of recovery symptoms. 15-keto-PGE2 was the only oxylipin with an interaction between inoculum dose and time. Acute 15-keto-PGE2 levels were inversely associated with symptoms during cold recovery in a multivariable analysis (P = .0043). CONCLUSIONS: These findings show that high 15-keto-PGE2 levels during the acute cold are associated with fewer symptoms during recovery.