Background Compositional differences in bronchial bacterial microbiota have been associated with asthma, but it remains unclear whether the findings are attributable to asthma, to aeroallergen sensitization or to inhaled corticosteroid treatment. Objectives To compare the bronchial bacterial microbiota in adults with steroid-naive atopic asthma (AA), with atopy but no asthma (ANA), and non-atopic healthy subjects (HC), and determine relationships of bronchial microbiota to phenotypic features of asthma. Methods Bacterial communities in protected bronchial brushings from 42 AA, 21 ANA, and 21 HC subjects were profiled by 16S rRNA gene sequencing. Bacterial composition and community-level functions inferred from sequence profiles were analyzed for between-group differences. Associations with clinical and inflammatory variables were examined, including markers of type 2-related inflammation and change in airway hyperresponsiveness following six weeks of fluticasone treatment. Results The bronchial microbiome differed significantly among the three groups. Asthmatic subjects were uniquely enriched in members of the Haemophilus, Neisseria., Fusobacterium, Porphyromonas and Sphingomonodaceae, and depleted in members of the Mogibacteriaceae and Lactobacillales. Asthma-associated differences in predicted bacterial functions included involvement of amino acid and short-chain fatty acid metabolism pathways. Subjects with type 2-high asthma harbored significantly lower bronchial bacterial burden. Distinct changes in specific microbiota members were seen following fluticasone treatment. Steroid-responsiveness was linked to differences in baseline compositional and functional features of the bacterial microbiome. Conclusion Even in mild steroid-naive asthma subjects, differences in the bronchial microbiome are associated with immunologic and clinical features of the disease. The specific differences identified suggest possible microbiome targets for future approaches to asthma treatment or prevention.

IMPORTANCE In asthma and other diseases, vitamin D insufficiency is associated with adverse outcomes. It is not known if supplementing inhaled corticosteroids with oral vitamin D3 improves outcomes in patients with asthma and vitamin D insufficiency. OBJECTIVE To evaluate if vitamin D supplementation would improve the clinical efficacy of inhaled corticosteroids in patients with symptomatic asthma and lower vitamin D levels. DESIGN, SETTING, AND PARTICIPANTS The VIDA (Vitamin D Add-on Therapy Enhances Corticosteroid Responsiveness in Asthma) randomized, double-blind, parallel, placebo-controlled trial studying adult patients with symptomatic asthma and a serum 25-hydroxyvitamin D level of less than 30 ng/mL was conducted across 9 academic US medical centers in the National Heart, Lung, and Blood Institute’s AsthmaNet network, with enrollment starting in April 2011 and follow-up complete by January 2014. After a run-in period that included treatment with an inhaled corticosteroid, 408 patients were randomized. INTERVENTIONS Oral vitamin D3 (100 000 IU once, then 4000 IU/d for 28 weeks; n = 201) or placebo (n = 207) was added to inhaled ciclesonide (320 µg/d). If asthma control was achieved after 12 weeks, ciclesonide was tapered to 160 µg/d for 8 weeks, then to 80 µg/d for 8 weeks if asthma control was maintained. MAIN OUTCOMES AND MEASURES The primary outcome was time to first asthma treatment failure (a composite outcome of decline in lung function and increases in use of β-agonists, systemic corticosteroids, and health care). RESULTS Treatment with vitamin D3 did not alter the rate of first treatment failure during 28 weeks (28%[95% CI, 21%-34%] with vitamin D3 vs 29% [95% CI, 23%–35%] with placebo; adjusted hazard ratio, 0.9 [95% CI, 0.6–1.3]). Of 14 prespecified secondary outcomes, 9 were analyzed, including asthma exacerbation; of those 9, the only statistically significant outcome was a small difference in the overall dose of ciclesonide required to maintain asthma control (111.3 µg/d [95% CI, 102.2–120.4 µg/d] in the vitamin D3 group vs 126.2 µg/d [95% CI, 117.2–135.3 µg/d] in the placebo group; difference of 14.9 µg/d [95% CI, 2.1–27.7 µg/d]). CONCLUSIONS AND RELEVANCE Vitamin D3 did not reduce the rate of first treatment failure or exacerbation in adults with persistent asthma and vitamin D insufficiency. These findings do not support a strategy of therapeutic vitamin D3 supplementation in patients with symptomatic asthma. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT01248065

No abstract

Asthma affects nearly 14 million people worldwide and has been steadily increasing in frequency for the past 50 years. Although environmental factors clearly influence the onset, progression, and severity of this disease, family and twin studies indicate that genetic variation also influences susceptibility. Linkage of asthma and related phenotypes to chromosome 6p21 has been reported in seven genome screens, making it the most replicated region of the genome. However, because many genes with individually small effects are likely to contribute to risk, identification of asthma susceptibility loci has been challenging. In this study, we present evidence from four independent samples in support of HLA-G as a novel asthma and bronchial hyperresponsiveness susceptibility gene in the human leukocyte antigen region on chromosome 6p21, and we speculate that this gene might contribute to risk for other inflammatory diseases that show linkage to this region.

No abstract