miR-140-5p Overexpression Protects Against Lipopolysaccharide-Induced Necrotizing Pneumonia via Targeting Toll-Like Receptor 4

Objective This study is to identify the effects of miRNA-140-5p on necrotizing pneumonia (NP) and its underlying mechanism. Methods The mRNA levels of miRNA-140-5p and TLR4 and secretion of IL-1β, IL-6, and TNF-α in peripheral blood from children with NP and healthy volunteers were determined using qRT-PCR and specific ELISAs. The interactions between miRNA-140-5p and TLR4 were investigated using a dual-luciferase reporter system. Cell viabilities were determined using a CCK-8 assay. qRT-PCR, western blotting, and specific ELISAs were applied to determine the expressions of genes in the cells. Peripheral blood from children with NP had significantly elevated levels of TLR4 but significantly lower levels of miR-140-5p compared to the control. Results Spearman’s rank correlation analysis showed a negative correlation between TLR4 and miR-140-5p. miR-140-5p regulated the expressions of TLR4 in A549 cells. Additionally, LPS induced a significant enhancement in the levels of TLR4 but significant reduction in the levels of miR-140-5p. The overexpression of miR-140-5p suppressed cell apoptosis and induced the release of inflammatory cytokines in the LPS-induced A549 cells. Conclusion The underlying mechanisms of miR-140-5p on the regulation of TLR4 are in part by the regulation of p65. The miR-140-5p inhibits necrotizing pneumonia by regulating TLR-4 via TNF–p65 signaling pathway.