MiR-382-5p suppresses M1 macrophage polarization and inflammatory response in response to bronchopulmonary dysplasia through targeting CDK8: Involving inhibition of STAT1 pathway.

Bronchopulmonary dysplasia (BPD) is an inflammation-related respiratory disorder in infants. MiR-382-5p has displayed low expression in developing lungs with BPD, while the effect of miR-382-5p on BPD remains elusive. Here, a hyperoxia (85% oxygen)-induced BPD model in neonatal mice was established. On postnatal days 10 and 15, hyperoxia reduced miR-382-5p expression in lungs of mice. Besides, CDK8, CD68 and CD86 levels were elevated on day 15 after birth, implying the involvement of CDK8 in M1 macrophage polarization. In addition, in vitro injury in RAW264.7 macrophages was induced by IFN-γ and LPS stimulation. Lentivirus-encoding miR-382-5p decreased CDK8 expression, alleviated the production of inflammatory cytokines TNF-α, IL-1β and IL-6, and restricted the levels of CD40 and CD86 in response to IFN-γ and LPS. Moreover, miR-382-5p inhibited the phosphorylation of STAT1. Luciferase reporter assay verified that miR-382-5p might target the 3'UTR of CDK8. Rescue assays revealed that CDK8 reversed the mitigating roles of miR-382-5p in inflammatory response and M1 macrophage polarization, as reflected by increased IL-6 and CD40 levels. Taken together, these findings indicate that miR-382-5p may suppress M1 macrophage activation and inflammatory response via inhibiting CDK8, thereby regulating the development of BPD, which is possibly mediated by STAT1 signaling.