MicroRNA-147b alleviates inflammation and apoptosis in acute lung injury via inhibition of p38 MAPK signaling pathway.

OBJECTIVE: The pathogenesis of acute lung injury (ALI) is complicated, the condition is developing rapidly, and the mortality rate is high. It is a common acute and critical illness in clinic. Here, we aimed to demonstrate the function and molecular mechanism of microRNA-147b (miR-147b) in ALI. MATERIALS AND METHODS: MiR-147b mimic or miR-147b inhibitor was transfected into A549 cells to upregulate or downregulate miR-147b. The inflammatory response of A549 cells was observed by measuring the levels of inflammatory cytokines (TNF-α, IL-6, IL-1ß) and chemokines (CCL2, CCL4) by enzyme-linked immunosorbent assay (ELISA) assay. The detection of apoptosis in A549 cells relies on Cell Counting Kit-8 (CCK-8) assay, caspase-3 activity assay, and flow cytometry. Quantitative Real Time-Polymerase Chain Reaction (RT-PCR) and Western blot were employed to detect the expression of miRNA and protein. RESULTS: MiR-147b was downregulated in lipopolysaccharide (LPS)-induced ALI rats and LPS-treated A549 cells. Upregulation of miR-147b markedly suppressed LPS-induced inflammation and apoptosis of A549 cells, which was manifested by the reduction of inflammatory cytokines (TNF-α, IL-6, IL-1ß) and chemokines (CCL2, CCL4), the reduction of LDH contents, the increase of cell viability, and the decrease of caspase-3 activity and apoptosis rate of A549 cells. The downregulation of miR-147b further induced inflammation and apoptosis of A549 cells caused by LPS, which was alleviated by inhibition of p38 MAPK pathway. CONCLUSIONS: Taken together, miR-147b was downregulated in ALI, and the overexpression of miR-147b inhibited LPS-induced inflammation and apoptosis in A549 cells via inhibition of p38 MAPK signaling pathway.