In the other study groups, three miRNAs were differentially expressed: miR-374a was down-regulated in COPD-BS vs C, miR-191-5p was up-regulated in COPD-BS vs H-BS, and miR-21-5p was down-regulated in COPD-TS compared to the C group.
Inhibition of miR-21 levels by tail vein injection of antagomir-21 into mice exposed to CS was used to demonstrate the role of miR-21 in airway remodeling leading to COPD in animals.
Accordingly, the levels of serum miR-21 and miR-181a as well as their ratios had a high sensitivity (0.854) and specificity (0.850) for evaluating the development of COPD.