Entry #: 15
Date: 24 September 2017
Section: High phenol olive oil and microarray
Topic: High phenol olive oil and gene expression changes
Type: Human metabolic syndrome trial

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OliveNetTM Journal Club

Expert review of literature related to olives and olive oil

D. Elizabeth McCord, Nancy B. Ray and Tom C. Karagiannis

Title

Gene expression changes in mononuclear cells in patients with metabolic syndrome after acute intake of phenol-rich virgin olive oil

Author(s)

Camargo A et al

Citation / Year

(1) / 2010

Keywords

Phenol-rich virgin olive oil, metabolic syndrome, microarray, peripheral blood mononuclear cells, anti-inflammatory pathways

Summary

Metabolic syndrome is a major clinical problem associated with obesity and increased for type 2 diabetes and cardiovascular disease (2). In this prospective double-blinded, randomized, crossover trial a total of 20 participants (nine M and 11 F) with metabolic syndrome, according to fulfilment of three or more criteria proposed by the Third Report of the National Cholesterol Education Program Expert Panel. The criteria include a number of parameters associated with metabolic syndrome including: obesity, hypertension, high fasting glucose, hypertriglyceridemia, and low high density lipoprotein (HDL, so-called good) cholesterol. Following a six week washout period and a 12 hour fast participants were given a breakfast intervention consisting of 60 g white bread, 40 mL virgin olive oil with either high or low phenolic content, and 60,000 IU of vitamin A per m2 of body surface area. Samples for further analysis were collected were up to four hours after the breakfast intervention.

Key points and implications

An interesting aspect of this trial is the preparation of the low-phenol (70 ppm phenolics) olive oil, essentially from the high-phenol virgin olive oil (398 ppm phenolics; from Canoliva®, Antonio Cano e Hijos™, Cordoba, Spain). The process involved a series of seven cycles of physical extraction in separating funnels and in the resulting oils hydroxytyrosol (an abundant antioxidant phenolic compound) was measured to be either 0.2 μmol per g (low phenolic content oil) or 45.4 μmol per g (high phenolic content olive oil). Firstly, the findings of the acute intervention indicated no significant change in metabolic parameters including glucose, insulin, non-sterified fatty acids, serum triglycerides and HDL). Microarrays probing 30,886 unique human genes was used to determine genome-wide changers in gene expression in isolated peripheral blood mononuclear cells, four hours following the breakfast intervention. Responses in key genes including JUN, PTGS2, EGR1, and IL1B were validated with quantitative real-time polymerase chain reaction and excellent correlation with the microarray experiments were observed. Overall, analysis of them microarray data indicated that the acute intervention with high-phenol olive oil resulted in the significant change of the expression of 98 genes (79 down-regulated and 19 up-regulated). Bioinformatics analysis indicated that the phenol-rich olive oil intervention may have induced an anti-inflammatory effect by regulating genes in various key pathway including the transcription factor NF-kB, activator protein- transcription factor complex AP-1, cytokine receptor interactions, arachidonic acid metabolic pathways, and mitogen-activated protein kinase pathways. These are very interesting findings and in general, corroborate some of the molecular effects observed with extracts and olive-oil phenolics in cell culture studies and in vivo studies. The raw data from this study has been deposited in the GEO database (accession number: GSE15812) and can be utilised as required for meta-analyses. It is anticipated that will become increasingly more important as further datasets are collected from microarray and next generation sequencing experiments. In this context, a recent interesting review provides an in-depth account of the current status (3).

Related publications

  1. A. Camargo et al., Gene expression changes in mononuclear cells in patients with metabolic syndrome after acute intake of phenol-rich virgin olive oil. BMC genomics 11, 253 (2010).
  2. C. Phillips, J. Lopez-Miranda, F. Perez-Jimenez, R. McManus, H. M. Roche, Genetic and nutrient determinants of the metabolic syndrome. Current opinion in cardiology 21, 185-193 (2006).
  3. G. Chiva-Blanch, L. Badimon, Effects of Polyphenol Intake on Metabolic Syndrome: Current Evidences from Human Trials. Oxidative medicine and cellular longevity 2017, 5812401 (2017).