Dataset Information

Potentially pathogenic airway bacteria and neutrophilic inflammation in treatment resistant severe asthma.

ABSTRACT:

Background

Molecular microbiological analysis of airway samples in asthma has demonstrated an altered microbiome in comparison to healthy controls. Such changes may have relevance to treatment-resistant severe asthma, particularly those with neutrophilic airway inflammation, as bacteria might be anticipated to activate the innate immune response, a process that is poorly steroid responsive. An understanding of the relationship between airway bacterial presence and dominance in severe asthma may help direct alternative treatment approaches.

Objective

We aimed to use a culture independent analysis strategy to describe the presence, dominance and abundance of bacterial taxa in induced sputum from treatment resistant severe asthmatics and correlate findings with clinical characteristics and airway inflammatory markers.

Methods

Induced sputum was obtained from 28 stable treatment-resistant severe asthmatics. The samples were divided for supernatant IL-8 measurement, cytospin preparation for differential cell count and Terminal Restriction Fragment Length Polymorphism (T-RFLP) profiling for bacterial community analysis.

Results

In 17/28 patients, the dominant species within the airway bacterial community was Moraxella catarrhalis or a member of the Haemophilus or Streptococcus genera. Colonisation with these species was associated with longer asthma disease duration (mean (SD) 31.8 years (16.7) vs 15.6 years (8.0), p?=?0.008), worse post-bronchodilator percent predicted FEV1 (68.0% (24.0) vs 85.5% (19.7), p?=?0.025) and higher sputum neutrophil differential cell counts (median (IQR) 80% (67-83) vs 43% (29-67), p?=?0.001). Total abundance of these organisms significantly and positively correlated with sputum IL-8 concentration and neutrophil count.

Conclusions

Airway colonisation with potentially pathogenic micro-organisms in asthma is associated with more severe airways obstruction and neutrophilic airway inflammation. This altered colonisation may have a role in the development of an asthma phenotype that responds less well to current asthma therapies.

SUBMITTER: Green BJ

PROVIDER: S-EPMC4067344 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Publications

Potentially pathogenic airway bacteria and neutrophilic inflammation in treatment resistant severe asthma.

Green Benjamin J BJ Wiriyachaiporn Surasa S Grainge Christopher C Rogers Geraint B GB Kehagia Valia V Lau Laurie L Carroll Mary P MP Bruce Kenneth D KD Howarth Peter H PH

PloS one 20140623 6

<h4>Background</h4>Molecular microbiological analysis of airway samples in asthma has demonstrated an altered microbiome in comparison to healthy controls. Such changes may have relevance to treatment-resistant severe asthma, particularly those with neutrophilic airway inflammation, as bacteria might be anticipated to activate the innate immune response, a process that is poorly steroid responsive. An understanding of the relationship between airway bacterial presence and dominance in severe ast ...[more]

PMID: 24955983

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Project description:Background: MicroRNAs are potent regulators of biologic systems that are critical to tissue homeostasis. Individual microRNAs have been identified in airway samples. However, a systems analysis of the microRNA-mRNA networks present in the sputum that contribute to airway inflammation in asthma has not been published. Methods: We conducted a genome-wide analysis of microRNA and messenger RNA (mRNA) in the sputum from patients with asthma and correlated expression with clinical phenotypes. Weighted gene correlation network analysis (WGCNA) was implemented to identify microRNA networks (modules) that significantly correlate with clinical features of asthma and mRNA expression networks. MicroRNA expression in peripheral blood neutrophils and lymphocytes, and in situ hybridization of the sputum were used to identify the cellular sources of microRNAs. MicroRNA expression obtained before and after ozone exposure was also used to identify changes associated with neutrophil counts in the airway. Results: Six microRNA modules were associated with clinical features of asthma. A single module (nely) was associated with a history of hospitalizations, lung function impairment, and numbers of neutrophils and lymphocytes in the sputum. Of the 12 microRNAs in the nely module, hsa-miR-223-3p was the highest expressed microRNA in neutrophils and was associated with increased neutrophil counts in the sputum in response to ozone exposure. Multiple microRNAs in the nely module correlated with two mRNA modules enriched for toll-like receptor (TLR) and Th17 signaling, and endoplasmic reticulum stress. Hsa-miR-223-3p was a key regulator of the TLR and Th17 pathways in the sputum of subjects with asthma. Conclusions: This study of sputum microRNA and mRNA expression from patients with asthma demonstrates the existence of microRNA networks and genes that are associated with features of asthma severity. Among these, hsa-miR-223-3p, a neutrophil-derived microRNA, regulates TLR/Th17 signaling and endoplasmic reticulum stress.

Dataset Information

Potentially pathogenic airway bacteria and neutrophilic inflammation in treatment resistant severe asthma.

Background

Objective

Methods

Results

Conclusions

Publications

Potentially pathogenic airway bacteria and neutrophilic inflammation in treatment resistant severe asthma.

Similar Datasets

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