Objective: Chronic obstructive pulmonary disease (COPD) is an inflammatory lung disease characterized by inflammatory cell activation and the release of inflammatory mediators. By measuring microRNA expression in the plasma of COPD subjects, we aimed to identify the clinical relevance of plasma miRNA levels in these patients.
Patients and methods: A total of 40 COPD patients and 40 healthy controls were enrolled in the study. The COPD model of C57BL/6 mice was also developed by exposing them to cigarette smoke (CS). The expression of microRNA-218-5p was detected by qRT-PCR in all the subjects and mice. The serum level of IL-18 and TGF-β1 was also detected via ELISA kit. To investigate the effects of miR-218-5p, 10 mg/kg of miR-218-5p inhibitor (miR-218-5p antagonist), a scrambled control or PBS (solvent) was intranasally administered on the first and the fourth exposure day, before the start of CS exposure.
Results: The results showed that miR-218-5p was significantly down-regulated in patients with COPD, compared to normal subjects. There was a negative correlation between the plasma miR-218-5p level and the duration of disease since diagnosis in COPD ex-smokers. CS-induced COPD mice experiments with a miR-218-5p inhibitor demonstrated a protective role of miR-218-5p in cigarette smoke-induced inflammation and COPD.
Conclusions: These findings supported that miR-218-5p may, therefore, play an important role in the pathogenesis of COPD.