Entry #: 8
Date: 8 August 2017
Section: Extra-virgin olive oil and microarray
Topic: Extra-virgin olive oil and gene expression
Type: Human volunteer trial
OliveNetTM Journal Club
Expert review of literature related to olives and olive oil
D. Elizabeth McCord, Nancy B. Ray and Tom C. Karagiannis
Genes and miRNA expression signatures in peripheral blood mononuclear cells in healthy subjects and patients with metabolic syndrome after acute intake of extra virgin olive oil
D’Amore et. al.
Citation / Year
(1) / 2016
Extra-virgin olive oil, phenolic compounds, gene expression, miRNA expression, microarray, human volunteer trial
Adherence to Mediterranean diet rich in extra-virgin olive oil is associated with beneficial numerous health effects. For example, protection from cardiovascular pathologies, cancer, diabetes and obesity have been linked to consumption of extra-virgin olive oil (2-6). An important current direction in the field to determine molecular mechanisms of action accounting for the beneficial effects of the Mediterranean diet and consumption of extra-virgin olive oil, at the molecular level in humans. In this study genome-wide expression analysis was performed to examine changes in gene and miRNA expression in human peripheral blood mononuclear cells (PBMC), following acute (4 hr) administration (single dose at 8 am, 50 mL [44 g] of extra-virgin olive oil). Two extra-virgin olive oils were utilised in this study; a relatively high polyphenol-content Coratina cultivar and a Peranzana cultivar containing relatively lower levels of polyphenols (both of the oils from Apulia [Italy], had a similar fatty acid composition). A total of 24 people (12 healthy individuals and 12 people at the first diagnosis of metabolic syndrome), were recruited for this study. During a one week period in which no olive oil consumption was permitted (wash-out), participants were placed on a low antioxidant diet for the first four days, followed by a restricted low-phenolic compound diet for three days. After the single dose of extra-virgin olive oil, participants were allowed only small quantities of water, and were not allowed to exercise for the four period. Blood samples were collected for biochemical analyses and for isolation of PBMC and RNA for microarray and RT-qPCR analyses. Standard methodologies were used for analyses of gene and miRNA expression using microarrays. The overall aim was to characterize gene and miRNA expression changes in healthy participants and people with metabolic syndrome following the single acute (4 hr) administration of extra-virgin olive oil.
Key points and implications
Interestingly, significant changes in the expression of genes and miRNA were observed using microarray technology, particularly in healthy participants, following a single administration (4 hr) of the high phenolic-content extra-virgin olive oil. An interesting aspect would be to further investigate the diminished effects observed in people with confirmed metabolic syndrome. Key findings were validated by conventional RT-qPCR. The authors provide a detailed account of specific genes up- (e.g. acyl-coA dehydrogenase, heat shock heat 70 kDa protein 1A, and peroxiredoxin 3) and down-regulated (e.g. sterol-C5-desaturase, interleukin-1 receptor-associated kinase 3, and cyclin K) and miRNA predominantly suppressed (e.g. miR-146b-5p, miR-19a-3p, and miR-107), following administration of high phenolic-content extra-virgin olive oil. In general, pathway analysis indicated changes in immunomodulation, oxidative stress and host of cadio-metabolic and cancer-related pathways were affected. Overall, this is study can be considered one of the early nutrigenomic approaches for examining the beneficial effects of consumption of extra-virgin olive oil at the molecular level in human participants. Further studies with larger participant cohorts, consumption of extra-virgin olive oil with varying levels of polyphenolic content, and for varying durations (more chronic consumption), will add the knowledge gained from this study, which provides a very useful starting point.
- S. D’Amore et al., Genes and miRNA expression signatures in peripheral blood mononuclear cells in healthy subjects and patients with metabolic syndrome after acute intake of extra virgin olive oil. Biochim Biophys Acta 1861, 1671-1680 (2016).
- E. Garcia-Fernandez, L. Rico-Cabanas, N. Rosgaard, R. Estruch, A. Bach-Faig, Mediterranean diet and cardiodiabesity: a review. Nutrients 6, 3474-3500 (2014).
- F. Cristina, Mediterranean diet health benefits may be due to a synergistic combination of phytochemicals and fatty-acids. BMJ 331, E366 (2005).
- G. Buckland, C. A. Gonzalez, The role of olive oil in disease prevention: a focus on the recent epidemiological evidence from cohort studies and dietary intervention trials. Br J Nutr 113 Suppl 2, S94-101 (2015).
- J. Lopez-Miranda et al., Olive oil and health: summary of the II international conference on olive oil and health consensus report, Jaen and Cordoba (Spain) 2008. Nutr Metab Cardiovasc Dis 20, 284-294 (2010).
- F. Violi et al., Extra virgin olive oil use is associated with improved post-prandial blood glucose and LDL cholesterol in healthy subjects. Nutr Diabetes 5, e172 (2015).