Sputum exosomes – promising biomarkers for idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive fibrosing interstitial lung disease of unknown aetiology which leads rapidly to death. As diagnosis of IPF is complex, we aimed to characterise microRNA (miRNA) content of exosomes from sputum of patients with IPF. Using miRNA quantitative PCR array, University of Liège researchers found a substantial dysregulation of sputum exosomal miRNA levels between patients with IPF and healthy subjects and identified a unique signature of three miRNAs. Interestingly, they found a negative correlation between miR-142-3p and diffusing capacity of the lungs for carbon monoxide/alveolar volume. This is the first characterisation of miRNA content of sputum-derived exosomes in IPF that identified promising biomarkers for diagnosis and disease severity.

Identification of a subset of exosomal microRNAs (miRNAs) dysregulated in the sputum of patients with idiopathic pulmonary fibrosis (IPF)

Characterisation of exosome-like vesicles released from sputum by (A) transmission electron microscopy, (B) dynamic light scattering analysis (140±19.1 nm, n=3) and (C) western blotting. Presence of exosomal markers, CD63, CD9, CD81 and mitochondrial protein cytochrome c in lysates from sputum-derived exosomes and cell lysate. (D) Principal component analysis plot on miRNA expression data from sputum-derived exosomes from healthy subjects (HS) and patients with IPF. (E) Volcano plot and (F) heat map of differentially expressed miRNAs across sputum-derived exosomes from HS and patients with IPF (fold change >1.3 and p<0.05). (G) Diseases and disorders or (H) functions annotation associated with exosomal miRNAs dysregulated in the sputum of patients with IPF predicted by ingenuity pathway analysis.

Njock MS, Guiot J, Henket MA, Nivelles O, Thiry M, Dequiedt F, Corhay JL, Louis RE, Struman I. (2018) Sputum exosomes: promising biomarkers for idiopathic pulmonary fibrosis. Thorax [Epub ahead of print]. [article]

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