Study of the potential anti-atherosclerotic effect of polyphenols from wild blueberry (Vaccinium angustifolium) in endothelial cells : preliminary data

Background: Atherosclerosis is a disease affecting arterial blood vessels caused largely by the accumulation of macrophages and white blood cells and promoted by low-density lipoproteins. Polyphenols may prevent atherosclerosis by reducing oxidative stress, inflammation, and by increasing the production of vasodilators such as nitric oxide. Aim: This study aims to investigate the capacity of an anthocyanin (ACN) and phenolic acid (PA)-rich fraction, obtained from a wild blueberry powder, to counteract early events in atherosclerosis in an in vitro cell model system. Methods: The anti-atheroclerotic effect of the two fractions was tested in human umbilical vein endothelial cells (HUVECs) commonly used as the in vitro model for the study of the function of endothelial cells. HUVECs were incubated with different concentrations (from 0.05 to 10 μg mL-1) of ACN and PA-rich fraction for 24h. Labelled monocytic THP-1 cells were added to HUVEC culture and the adhesion was promoted by stimulating a pro-inflammatory status with TNF- (1 μg mL-1). After 24h incubation, the attachment of THP-1 to HUVEC was measured through a fluorescence spectrophotometer and the fold-increase in THP-1 attachment with respect to the control (without stimulation with TNF-) was calculated. Results were analysed by ANOVA. Post-hoc analysis of differences between treatments was assessed by the Least Significant Difference (LSD) test with p ≤ 0.05 as level of statistical significance. Results: We documented that ACN and PA-rich fractions reduced THP-1 attachment to HUVEC cells following stimulation with the pro-inflammatory cytokine. In particular, ACN-rich fraction showed a positive and significant effect at the concentration of 10 μg mL-1 (-33%, p=0.04), while the PA-rich fraction was able to reduce significantly THP-1 attachment at the low doses (0.05, 0.1 and 0.3 μg mL-1, -45%, -49% and -51%, respectively). Conclusions: These preliminary results demonstrated a potential role of polyphenol compounds in the prevention of atherosclerotic process by reducing the THP-1 attachment to HUVEC cells. Moreover, the effects were observed also at the low concentrations, supporting a possible contribution at concentrations comparable with those achievable in vivo. The role of ACNs, their metabolites and the molecular mechanisms involved in such modulation are under study.