Exosome-enclosed microRNAs in exhaled breath hold potential for biomarker discovery in patients with pulmonary diseases

Abstract

To the Editor: MicroRNAs (miRNAs) are small noncoding RNAs of 22 to 25 nucleotides in length that act through an RNA-induced silencing complex to posttranscriptionally regulate mRNAs that contain complementary sequences. Highly stable circulating miRNAs are found in biological fluids and are potential biomarkers.1, 2 These are often enclosed in small secretory membrane vesicles called exosomes, which permit transfer of miRNA between cells.3 Exhaled breath condensate (EBC), which can be obtained noninvasively and conveniently and is representative of the airway lining fluid, could be an ideal substrate for discovery of pulmonary disease biomarkers.4, 5, 6 For the first time, we report that miRNAs can be reliably detected in EBC by using quantitative PCR analysis and are suitable as biomarkers.