Nutrigenomic Effect of Hydroxytyrosol in Vascular Endothelial Cells: A Transcriptomic Profile Analysis

Maria Annunziata Carluccio,Raffaele De Caterina,Nadia Calabriso,Egeria Scoditti,Rosanna Martinelli,Tiziano Verri,Valentina Gatta,Marika Massaro,Michele Maffia

doi:10.3390/nu13113990

Abstract

Hydroxytyrosol (HT), a peculiar olive and olive oil phenolic antioxidant, plays a significant role in the endothelial and cardiovascular protection associated with olive oil consumption. However, studies examining the effects of HT on the whole-genome expression of endothelial cells, which are prominent targets for vasculo-protective effects of olive oil polyphenols, have been lacking. This study aims to comprehensively evaluate the genomic effects exerted by HT, at the transcriptional level, in endothelial cells under resting or proinflammatory conditions. Human umbilical vein endothelial cells (HUVECs) were treated with 10 µmol/L HT for 1 h and then stimulated with 5 ng/mL interleukin (IL)-1β for 3 h. Total RNA was extracted, and gene expression profile assessed with microarray analysis. Functional enrichment analysis and pathway analysis were performed by Ingenuity Pathways Analysis. Microarray data were validated by qRT-PCR. Fixing a significance threshold at 1.5-fold change, HT affected the expression of 708 and 599 genes, respectively, in HUVECs under resting and IL-1β-stimulated conditions; among these, 190 were common to both conditions. Unfolded protein response (UPR) and endoplasmic reticulum stress resulted from the two top canonical pathways common between HT and HT-IL-1β affected genes. IL-17F/A signaling was found in the top canonical pathways of HT modified genes under resting unstimulated conditions, whereas cardiac hypertrophy signaling was identified among the pathways affected by HT-IL-1β. The transcriptomic analysis allowed pinpointing immunological, inflammatory, proliferative, and metabolic-related pathways as the most affected by HT in endothelial cells. It also revealed previously unsuspected genes and related gene pathways affected by HT, thus broadening our knowledge of its biological properties. The unbiased identification of novel genes regulated by HT improves our understanding of mechanisms by which olive oil prevents or attenuates inflammatory diseases and identifies new genes to be enquired as potential contributors to the inter-individual variation in response to functional food consumption.

Highlights

The Mediterranean diet is recognized as a cornerstone of chronic disease prevention.Adherence to a Mediterranean diet style reduces the risk of cardiovascular and neurodegenerative diseases and even premature death overall [1,2,3]
In a randomized crossover trial [11], gene expression microarray analysis on peripheral blood mononuclear cells (PBMCs) isolated from patients with metabolic syndrome revealed that a breakfast based on virgin olive oil, high in polyphenols (398 ppm), repressed the expression of proinflammatory genes, linked to atherosclerosis, obesity, dyslipidemia, and type 2 diabetes mellitus when compared with common olive oil [11]
In an in vitro model of early atherogenesis consisting of cultured human umbilical vein endothelial cells (HUVECs) activated by proinflammatory and proatherosclerotic triggers, we have previously found that olive oil polyphenols with antioxidant activity, including HT, significantly inhibited events connected with endothelial activation, along with the expression of adhesion molecules such as VCAM-1, E-selectin and, to a lesser extent, ICAM-1, after stimulation with virtually any stimulus able to elicit the coordinated expression of such genes [17,18,19]

Summary

Introduction

The Mediterranean diet is recognized as a cornerstone of chronic disease prevention.Adherence to a Mediterranean diet style reduces the risk of cardiovascular and neurodegenerative diseases and even premature death overall [1,2,3]. Crucial supportive studies demonstrated that minor components of olive oil, HT and derivatives, reduce atherosclerotic risk factors, improve plasma lipid levels, and repair oxidative damage related to cardiovascular diseases [7]. Besides reducing oxidative stress markers and atherosclerotic risk factors, olive oil polyphenols induce beneficial changes in the expression profile of genes involved in atherosclerosis, vascular inflammation, and oxidative stress [10]. Microarray reports indicated that, in healthy volunteers, an acute or chronic intake of virgin olive oil induced changes in gene expression related to insulin resistance, oxidative stress, and inflammation [10]. Following the results from human intervention trials, in vitro studies using cell model systems relevant to cardiovascular diseases, such as vascular endothelial cells and monocytes/macrophages, reinforce the nutrigenomic effects of olive oil polyphenols as a mechanism for their vasculo-protective role [12]

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