MiR-124-3p targeting PDE4B attenuates LPS-induced ALI through the TLR4/NF-κB signaling pathway.

• This study firstly proved that miR-124-3p targeting PDE4B had an anti-inflammation protective effect on LPS-induced ALI by inhibiting TLR4/NF-κB signaling pathway. • This study provides novel insights into miR-124-3p-directed therapeutic strategies for ARDS patients. • This study provides novel insights that miR-124-3p could be a novel, promising and specific method to inhibit PDE4B. • The potential therapeutic effect of miR-124-3p will need to be evaluated based on further clinical experiments. A large number of studies have found that microRNAs (miRNAs) and phosphodiesterase 4 (PDE4) are crucial regulators of inflammatory responses in acute lung injury (ALI). This study will explore the protective effect of miR-124-3p on ALI and its related mechanism. The ALI mouse model was established by intratracheal administration of lipopolysaccharide (LPS) and evaluated by haematoxylin and eosin (HE) staining, lung injury score, inflammation factors, polymorphonuclear leukocyte (PMN) count, total protein and lung wet weight/dry weight (W/D) ratio. MiR-124-3p was overexpressed in vivo by intratracheal administration of miR-agomir, and PDE4B was expressed at low level in vivo by intratracheal administration of a PDE4B inhibitor. The mRNA expression level was detected by qRT–PCR, and the protein expression level was detected by Western blot. The relationship between miR-124-3p and PDE4B was detected by dual-luciferase activity assay. We found that miR-124-3p was downregulated in LPS-induced ALI. Overexpression of miR-124-3p alleviated lung injury by inhibiting the Toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) signaling pathway. Furthermore, we confirmed that miR-124-3p suppressed the TLR4/NF-κB signaling pathway by directly targeting PDE4B. miR-124-3p targeting PDE4B had a protective effect on LPS-induced ALI by inhibiting the TLR4/NF-κB signaling pathway. [ABSTRACT FROM AUTHOR]