Ssc-novel-miR-106-5p reduces lipopolysaccharide-induced inflammatory response in porcine endometrial epithelial cells by inhibiting the expression of the target gene mitogen-activated protein kinase kinase kinase 14 (MAP3K14)

As an important gram-negative bacterial outer membrane component, lipopolysaccharide (LPS) plays an important role in bacterial-induced endometritis in sows. However, how LPS induces endometritis is unclear. We stimulated sow endometrial epithelial cells (EECs) with LPS and detected cell viability and tumour necrosis factor-α (TNF-α) and interleukin-1 (IL-1) secretion. LPS affected EEC viability and TNF-α and IL-1 secretion in a dose-dependent manner. LPS induced differential expression in 10 of 393 miRNAs in the EECs (downregulated, nine; upregulated, one). MicroRNA (miRNA) high-throughput sequencing of the LPS-induced EECs plus bioinformatics analysis and the dual-luciferase reporter system revealed a novel miRNA target gene: mitogen-activated protein kinase kinase kinase 14 (MAP3K14). Ssc-novel-miR-106-5p mimic, inhibitor and the nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (IκBα) phosphorylation inhibitor Bay11-7085 were used to detect EEC nuclear factor-κB phosphorylation levels (p-NF-κB) and TNF-α and IL-1 secretion. MiR-106-5p mimic downregulated MAP3K14 mRNA and protein expression levels, inhibited p-NF-κB levels and decreased IL-1 and TNF-α secretion, whereas miR-106-5p inhibitor had the opposite effect. Bay11-7085 inhibited p-NF-κB expression and TNF-α and IL-1 secretion. These results suggest that LPS downregulates ssc-novel-miR-106-5p expression in sow EECs to increase MAP3K14 expression, which increases p-NF-κB to promote IL-1 and TNF-α secretion.