Abstract
This study investigated the atheroprotective properties of olive oil polyphenol, hydroxytyrosol (HT), in combination with carbon monoxide-releasing molecule-2 (CORM-2) that acts as a carbon monoxide donor using vascular endothelial cells (VECs). Our results showed that CORM-2 could strengthen the cytoprotective and anti-apoptotic effects of HT against TNF alpha-induced cellular damage by enhancing cell survival and the suppression of caspase-3 activation. While HT alone attenuated NF kappa Bp65 phosphorylation and I kappa B alpha degradation triggered by TNF alpha in a dose-dependent manner, combined treatment of HT with CORM-2 but not iCORM-2 nearly completely blocked these TNF alpha effects. Furthermore, combined action of both compounds results in the inhibition of NF kappa B nuclear translocation. Results also indicate that both compounds time-dependently increased eNOS phosphorylation levels and the combination of HT with CORM-2 was more effective in enhancing eNOS activation and NO production in VECs. The NOS inhibitor, L-NMMA, significantly suppressed the combined effects of HT and CORM-2 on TNF alpha-triggered NF kappa Bp65 and I kappa B alpha phosphorylation as well as decreased cell viability. Together, these data suggest that carbon monoxide-dependent regulation of NO production by the combination of HT with CORM-2 may provide a therapeutic benefit in the treatment of endothelial dysfunction and atherosclerosis.