Sulfated and Glucuronated trans-Resveratrol Metabolites Regulate Chemokines and Sirtuin-1 Expression in U-937 Macrophages

The natural anti-inflammatory compound resveratrol (RES) is metabolized upon ingestion. After dietary-scale doses, plasma concentrations of sulfated and glucuronated metabolites in humans exceed those of RES. The aim of this, in vitro study was to assess the effect of physiological concentrations (1 mu M) of the most abundant RES metabolites (RES-3-O-sulfate, R3S; RES-disulfates, RdS; RES-3-O-glucuronide, R3G; RES-4'-O-glucuronide, R4G) on genes and proteins involved in immune cell chemotaxis and inflammation (IL-8, MIP-1b, MCP-1, CCR1, CCR2, CXCR2, SIRT1) in a cell model of lipopolysatcharide (LPS)-activated U-937 macrophages. Levels of MCP-1 mRNA were comparably decreased after 3 h of treatment with R3S and RdS by -24.7 +/- 5.51 and -28.7 +/- 19.2%, respectively. LPS-induced MCP-1 protein release was reduced after 3 h of treatment by R3S (-20.8 +/- 13.9%) and RdS (-25.7 +/- 8.29%). After a 9 h treatment, RdS also inhibited IL-8 and MT-1b protein release by -22.9 +/- 3.57 and -20.1 +/- 7.00%, respectively. Glucuronides showed differential effects after 6 h of treatment, With R4G upregulating mRNA of MIP-1b (24.5 +/- 14.8%) and R3G and R4G down-regulating CXCR2 surface protein compared to cells treated with LPS alone, by -5.33 +/- 4.18 and -15.2 +/- 5.99%, respectively. On the contrary, R3G and R4G up-regulated SIRT1 mRNA by 22.7 +/- 17.9 and 22.8 +/- 16.9%, respectively, in LPS-stimulated U-937 macrophages, showing anti-inflammatory properties. In conclusion, sulfated RES metabolites show an interesting beneficial potential for attenuating inflammatory immune processes.