MicroRNA expression profiling in mild asthmatic human airways and effect of corticosteroid therapy.
BACKGROUND
Asthma is a common disease characterised by reversible airflow obstruction, bronchial hyperresponsiveness and chronic inflammation, which is commonly treated using corticosteroids such as budesonide. MicroRNAs (miRNAs) are a recently identified family of non-protein encoding genes that regulate protein translation by a mechanism entitled RNA interference. Previous studies have shown lung-specific miRNA expression profiles, although their importance in regulating gene expression is unresolved. We determined whether miRNA expression was differentially expressed in mild asthma and the effect of corticosteroid treatment.


RESULTS
We have examined changes in miRNA using a highly sensitive RT-PCR based approach to measure the expression of 227 miRNAs in airway biopsies obtained from normal and mild asthmatic patients. We have also determined whether the anti-inflammatory action of corticosteroids are mediated through miRNAs by determining the profile of miRNA expression in mild asthmatics, before and following 1 month twice daily treatment with inhaled budesonide. Furthermore, we have analysed the expression of miRNAs from individual cell populations from the airway and lung. We found no significant difference in the expression of 227 miRNAs in the airway biopsies obtained from normal and mild asthmatic patients. In addition, despite improved lung function, we found no significant difference in the miRNA expression following one month treatment with the corticosteroid, budesonide. However, analysis of bronchial and alveolar epithelial cells, airway smooth muscle cells, alveolar macrophages and lung fibroblasts demonstrate a miRNA expression profile that is specific to individual cell types and demonstrates the complex cellular heterogeneity within whole tissue samples.


CONCLUSIONS
Changes in miRNA expression do not appear to be involved in the development of a mild asthmatic phenotype or in the anti-inflammatory action of the corticosteroid budesonide.
Williams
Andrew E
AE
Biopharmaceutics Research Group, National Heart and Lung Institute, Imperial College, London, United Kingdom. a.williams@imperial.ac.uk
Larner-Svensson
Hanna
H
Perry
Mark M
MM
Campbell
Gaynor A
GA
Herrick
Sarah E
SE
Adcock
Ian M
IM
Erjefalt
Jonas S
JS
Chung
Kian Fan
KF
Lindsay
Mark A
MA
D000293:Adolescent; D000305:Adrenal Cortex Hormones / Q000627:therapeutic use*; D000328:Adult; D001249:Asthma / Q000188:drug therapy*; D001706:Biopsy; D001980:Bronchi / Q000187:drug effects / Q000378:metabolism*; D019819:Budesonide / Q000627:therapeutic use; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D007249:Inflammation / Q000188:drug therapy; D008168:Lung / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D035683:MicroRNAs / Q000378:metabolism*; D011650:Pulmonary Alveoli / Q000187:drug effects / Q000378:metabolism*
D000305:Adrenal Cortex Hormones; D035683:MicroRNAs; D019819:Budesonide