Oleacein may inhibit destabilization of carotid plaques from hypertensive patients. Impact on high mobility group protein-1

Background: In patients with hypertension the haemorrhage into carotid atherosclerotic plaque increases risk of plaque destabilization and rupture. Our previous study showed that oleacein, a secoiridoid present in extra virgin olive oil, enhanced uptake of haemoglobin-haptoglobin complex and change macrophage phenotype from pro-inflammatory M1 to anti-inflammatory M2. Purpose: The aim this study was to investigate a potential role of oleacein in attenuation of carotid plaque destabilisation ex vivo. Methods: Samples of atherosclerotic plaque were harvested from 20 patients with hypertension /11 women and 9 men/, who underwent carotid endarterectomy after transient ischemic attacks. Matching pieces of each plaque were incubated with increased concentration of pure oleacein /range 0-20 mu M/for 24 h. HMGB1, MMP-9, MMP9/NGAL, TF and IL-10, as well as HO-1 secretion from plaque was measured by enzyme-linked immunosorbent assay /ELISA/. Statistical significance was set at P < 0.05 and P < 0.001. Results: Oleacein at the concentrations of 10 and 20 mu M significantly (P < 0.001) decreased secretion of HMGB1 (up 90%), MMP-9 (up to 80%), MMP-9/NGAL complex (up to 80%) and TF (more than 90%) from the treated plaque, as compared to control. At the same time IL-10 and HO-1 release increased by more than 80% (P < 0.001). Conclusion: Our results indicate that oleacein possess ability to attenuate the destabilization of carotid plaque and could be potentially useful in the reduction of ischemic stroke risk.