The protective effect of hydroxytyrosol acetate against inflammation of vascular endothelial cells partly through the SIRT6-mediated PKM2 signaling pathway

Hydroxytyrosol acetate (HT-AC), a polyphenolic compound in olive oil, exerts an anti-inflammatory effect on murine collagen-induced arthritis. However, the effect of HT-AC on inflammatory response in cardiovascular disease remains unclear. Thus, in this study, we aimed to investigate the effect of HT-AC on the inflammation response of vascular endothelial cells and the related molecular mechanism. Our results showed that HT-AC inhibited the inflammatory response in hypercholesterolemic mice and tumor necrosis factor (TNF)-stimulated HUVECs. Meanwhile, HT-AC also up-regulated SIRT6 expression in hypercholesterolemic mice and HUVECs. To further investigate whether SIRT6 is involved in the regulation of endothelial inflammatory response by HT-AC, endothelium-specific Sirt6 knockout (Sirt6^endo-/-) mice were used. Our study found that Sirt6^endo-/- abolished the inhibition of inflammatory response by HT-AC in the thoracic aorta of hypercholesterolemic mice. In vitro study also showed that knockdown of SIRT6 reduced the inhibition of inflammatory response by HT-AC, whereas overexpression of SIRT6 augmented the inhibition of inflammatory response by HT-AC in HUVECs. Further study demonstrated that HT-AC exerts its anti-inflammatory effect partly via the SIRT6-mediated PKM2 signaling pathway. In addition, HT-AC inhibited TNF-induced inflammatory response through the TNF receptor superfamily member 1A (TNFRSF1A) signaling pathway. These findings indicate that HT-AC regulates the vascular endothelial inflammatory response partly through the TNFRSF1A/SIRT6/PKM2-mediated signaling pathway.