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

Abstract

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. 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-1β) 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. 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-1β) 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. 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.