MiR-221-3p and miR-92a-3p enhances smoking-induced inflammation in COPD

Background Smoking is likely to facilitate airway inflammation and finally contributes to chronic obstructive pulmonary disease (COPD). This investigation was intended to elucidate miRNAs that were involved in smoking-induced COPD. Methods Altogether 155 COPD patients and 77 healthy volunteers were recruited, and their serum levels of miR-221-3p and miR-92a-3p were determined. Besides, human bronchial epithelial cells (16HBECs) were purchased, and they were treated by varying concentrations of cigarette smoke extract (CSE). The 16HBECs were, additionally, transfected by miR-221-3p mimic, miR-92a-3p mimic, miR-221-3p inhibitor or miR-92a-3p inhibitor, and cytokines released by them, including TNF-alpha, IL-8, IL-1 beta, and TGF-beta 1, were monitored using enzyme linked immunosorbent assay (ELISA) kits. Results Chronic obstructive pulmonary disease patients possessed higher serum levels of miR-221-3p and miR-92a-3p than healthy volunteers (p < 0.05), and both miR-221-3p and miR-92a-3p were effective biomarkers in diagnosing stable COPD from acute exacerbation COPD. Moreover, viability of 16HBECs was undermined by CSE treatment (p < 0.05), and exposure to CSE facilitated 16HBECs' release of TNF-alpha, IL-8, IL-1 beta, and TGF-beta 1 (p < 0.05). Furthermore, miR-221-3p/miR-92a-3p expression in 16HBECs was significantly suppressed after transfection of miR-221-3p/miR-92a-3p inhibitor (p < 0.05), which abated CSE-triggered increase in cytokine production and decline in viability of 16HBECs (p < 0.05). Conclusion MiR-221-3p and miR-92a-3p were involved in CSE-induced hyperinflammation of COPD, suggesting that they were favorable alternatives in diagnosing COPD patients with smoking history.

Automated summary

The study found that COPD patients had higher levels of miR-221-3p and miR-92a-3p in their serum compared to healthy volunteers, which were effective biomarkers in diagnosing stable COPD from acute exacerbation COPD. Exposure to cigarette smoke extract (CSE) weakened the viability of 16HBECs and led to increased release of inflammatory cytokines. Suppression of miR-221-3p/miR-92a-3p expression in 16HBECs after transfection with inhibitors reduced CSE-induced inflammation, suggesting these miRNAs as potential diagnostic markers for COPD patients with a smoking history.