title: Asthma inflammatory phenotypes show differential microRNA expression in sputum.
abstract: Asthma is classified according to severity and inflammatory phenotype and is likely to be distinguished by specific microRNA (miRNA) expression profiles.
  
  
  
  We sought to associate miRNA expression in sputum supernatants with the inflammatory cell profile and disease severity in asthmatic patients.
  
  
  
  We investigated miRNA expression in sputum supernatants of 10 healthy subjects, 17 patients with mild-to-moderate asthma, and 9 patients with severe asthma using high-throughput, stem-loop, reverse transcriptase quantitative real-time PCR miRNA expression profiling (screening cohort, n = 36). Differentially expressed miRNAs were validated in an independent cohort (n = 60; 10 healthy subjects and 50 asthmatic patients). Cellular miRNA origin was examined by using in situ hybridization and reverse transcriptase quantitative real-time PCR. The functional role of miRNAs was assessed by using in silico analysis and in vitro transfecting miRNA mimics in human bronchial epithelial cells.
  
  
  
  In 2 independent cohorts expression of miR-629-3p, miR-223-3p, and miR-142-3p was significantly upregulated in sputum of patients with severe asthma compared with that in healthy control subjects and was highest in patients with neutrophilic asthma. Expression of the 3 miRNAs was associated with sputum neutrophilia, and miR-223-3p and miR-142-3p expression was associated also with airway obstruction (FEV1/forced vital capacity). Expression of miR-629-3p was localized in the bronchial epithelium, whereas miR-223-3p and miR-142-3p were expressed in neutrophils, monocytes, and macrophages. Transfecting human bronchial epithelial cells with miR-629-3p mimic induced epithelial IL-8 mRNA and protein expression. IL-1β and IL-8 protein levels were significantly increased in sputum of patients with severe asthma and were positively associated with sputum neutrophilia.
  
  
  
  Expression of miR-223-3p, miR-142-3p, and miR-629-3p is increased in sputum of patients with severe asthma and is linked to neutrophilic airway inflammation, suggesting that these miRNAs contribute to this asthma inflammatory phenotype.
authors.affiliation: Department of Respiratory Medicine, Ghent University Hospital, Ghent, Belgium. Electronic address: Tania.Maes@UGent.be.
authors.forename: Tania
authors.initials: T
authors.lastname: Maes
authors.affiliation: Center for Medical Genetics, Ghent University, Ghent, Belgium.
authors.forename: Francisco Avila
authors.initials: FA
authors.lastname: Cobos
authors.affiliation: Department of Respiratory Medicine, CHU Sart-TilmanB35, Liege, Belgium.
authors.forename: Florence
authors.initials: F
authors.lastname: Schleich
authors.affiliation: Department of Clinical and Biological Sciences, University of Torino, Torino, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Sorbello
authors.affiliation: Department of Respiratory Medicine, CHU Sart-TilmanB35, Liege, Belgium.
authors.forename: Monique
authors.initials: M
authors.lastname: Henket
authors.affiliation: Center for Medical Genetics, Ghent University, Ghent, Belgium.
authors.forename: Katleen
authors.initials: K
authors.lastname: De Preter
authors.affiliation: Department of Respiratory Medicine, Ghent University Hospital, Ghent, Belgium.
authors.forename: Ken R
authors.initials: KR
authors.lastname: Bracke
authors.affiliation: Department of Respiratory Medicine, Ghent University Hospital, Ghent, Belgium.
authors.forename: Griet
authors.initials: G
authors.lastname: Conickx
authors.affiliation: Department of Cellular and Molecular Immunology, GIGA-Research Centre and Faculty of Veterinary Medicine, University of Liege, Liege, Belgium.
authors.forename: Claire
authors.initials: C
authors.lastname: Mesnil
authors.affiliation: Center for Medical Genetics, Ghent University, Ghent, Belgium.
authors.forename: Jo
authors.initials: J
authors.lastname: Vandesompele
authors.affiliation: Department of Respiratory Medicine, Ghent University Hospital, Ghent, Belgium.
authors.forename: Lies
authors.initials: L
authors.lastname: Lahousse
authors.affiliation: Department of Cellular and Molecular Immunology, GIGA-Research Centre and Faculty of Veterinary Medicine, University of Liege, Liege, Belgium.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Bureau
authors.affiliation: Center for Medical Genetics, Ghent University, Ghent, Belgium.
authors.forename: Pieter
authors.initials: P
authors.lastname: Mestdagh
authors.affiliation: Department of Respiratory Medicine, Ghent University Hospital, Ghent, Belgium.
authors.forename: Guy F
authors.initials: GF
authors.lastname: Joos
authors.affiliation: Department of Clinical and Biological Sciences, University of Torino, Torino, Italy.
authors.forename: Fabio L M
authors.initials: FL
authors.lastname: Ricciardolo
authors.affiliation: Department of Respiratory Medicine, Ghent University Hospital, Ghent, Belgium.
authors.forename: Guy G
authors.initials: GG
authors.lastname: Brusselle
authors.affiliation: Department of Respiratory Medicine, CHU Sart-TilmanB35, Liege, Belgium.
authors.forename: Renaud
authors.initials: R
authors.lastname: Louis
mesh_terms: D000328:Adult; D000368:Aged; D001249:Asthma / Q000235:genetics* / Q000276:immunology / Q000378:metabolism / Q000503:physiopathology; D001980:Bronchi / Q000166:cytology; D016207:Cytokines / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000378:metabolism*; D008875:Middle Aged; D009504:Neutrophils / Q000276:immunology; D010641:Phenotype; D013183:Sputum / Q000378:metabolism*
chemical_list: D016207:Cytokines; D035683:MicroRNAs
keywords: Asthma; microRNA; neutrophilic inflammation; sputum