A sputum gene expression signature of six biomarkers identifies asthma inflammatory phenotype and steroid responsiveness

This study identifies differentially expression genes in the sputum of people with eosinophilic, neutrophilic and paucigranulocytic asthma. A selection of markers identified using this microarray were further validated using qPCR on a wider sample set. Gene expression profiles were generated from induced sputum samples from 47 asthma patients and were grouped by the inflammatory phenotype assigned using sputum cell counts into neutrophilic asthma (n=12), eosinophilic asthma (n=17) and paucigranulocytic asthma (n=18). RNA was extracted, amplified and hybridised to Illumina Sentrix HumanRef-8 Version 2 Expression BeadChips, and genes that were differentially expressed between asthma inflammatory phenotypes were compared.