Sodium acetate inhibits Staphylococcus aureus internalization into bovine mammary epithelial cells by inhibiting NF-κB activation.

Bovine mastitis is one of the most costly and prevalent disease affecting dairy cows worldwide. It was reported that Staphylococcus aureus could internalize into bovine mammary epithelial cells (bMEC) and induce mastitis. Some short chain fatty acids (SCFA) have shown to suppress S. aureus invasion into bMEC and regulate antimicrobial peptides expression. But it has not been evaluated that sodium acetate has the similar effect. The aim of this study was to investigate the effect of sodium acetate on the invasion of bovine mammary epithelial cells (bMEC) by S. aureus. Gentamicin protection assay showed that the invasion of S. aureus into bMEC was inhibited by sodium acetate in a dose-dependent manner. Sodium acetate (0.25-5 mM) did not affect S. aureus growth and bMEC viability. The TAP gene level was decreased, while the BNBD5 mRNA level was enhanced in sodium acetate treated bMEC. In sodium acetate treated and S. aureus challenged bMEC, the TAP gene expression was increased and BNBD5 gene expression was not modified at low concentrations, but decreased at high concentrations. The Nitric oxide (NO) production of bMEC after S. aureus stimulation was decreased by sodium acetate treatment. Furthermore, sodium acetate treatment suppressed S. aureus-induced NF-κB activation in bMEC in a dose manner. In conclusion, our results suggested that sodium acetate exerts an inhibitory property on S. aureus internalization and modulates antimicrobial peptides gene expression.