miR-122-5p and miR-191-5p are increased in plasma small extracellular vesicles in asthma

Background: miRNAs are critically involved in asthma and are actively secreted in extracellular vesicles (EV) for inter-cell communication. We have previously shown that total extracellular miRNAs in plasma can distinguish between asthma and healthy controls (Milger, Allergy, 2017). Thus, we now aimed to investigate if miRNA profiles from plasma EVs are altered in patients with asthma. Methods: We isolated EVs from 1 mL plasma of adult subjects from the ALLIANCE cohort with mild-to-moderate (AM) or severe asthma (AS), and healthy controls (HC) (n=15/group) by size exclusion chromatography (Izon). EVs were characterized by nanoparticle-tracking analysis and flow cytometry. EV RNA was isolated and subjected to small RNA-seq (Illumina). We correlated sequencing data with clinical characteristics and confirmed candidate miRNAs in a new set of EV isolates by RT-qPCR. Results: Isolated EVs had a median size of 131.5 nm and a median concentration of 8.6x10^9 particles/mL in HC, with no significant differences among the groups. RNA-seq detected 139 EV-miRNAs, 35 of which were expressed at moderate to high levels. miR-122-5p was significantly higher in EVs from AS patients compared to HC (log2FC=1.77, padj=0.019) and we observed a trend for miR-191-5p (log2FC=0.39, padj=0.11). Both findings were confirmed by RT-qPCR. Further, miR-191-5p significantly correlated with FEV1%pred (R=-0.38 p=0.013), eosinophil (R=0.45, p=0.0056) and neutrophil (R=-0.37, p=0.027) counts in blood. Conclusion: miR-122-5p and miR-191-5p are increased in EVs from subjects with asthma, and miR-191-5p correlates with lung function impairment and inflammation. Therefore, EV miRNAs might qualify for disease subphenotyping in asthma.