Entry #: 53
Date: 31 May 2018
Section: Phenolic extracts
Topic: Phenolic extracts and oxysterols
Type: In vitro model
OliveNetTM Journal Club
Expert review of literature related to olives and olive oil
D. Elizabeth McCord, Nancy B. Ray and Tom C. Karagiannis
Olive oil polyphenols reuce oxysterols-induced redox imbalance and pro-inflammatory response in interstinal cells
Serra et al
Citation / Year
(1) / 2018
Phenolic extract, olive phenolics, intestinal cells, CaCo-2 enterocytes, cholesterol, oxysterols, inflammation
Chronic gastrointestinal disorders including inflammatory bowel diseases, are typified the production of pro-inflammatory cytokines and chemokines from the local environment (enterocytes and immune cells), excessive nitric oxide, and oxidative radical formation (2, 3). In this context, it is becoming increasingly evident that a pro-inflammatory diet is associated with the onset and progression of inflammatory gastrointestinal disorders (4). For example, oxidized products of dietary cholesterol (oxysterols), have been shown to cause damage in the colon (epithelial barrier) due to their pro-inflammatory properties, and have been associated with inflammatory bowel diseases and colon cancer (5-10). In this study, the effects of olive phenolics in ameliorating the pro-inflammatory effects of oxysterols in epithelial cells was investigated. The well-known antioxidant and anti-inflammatory effects of olive phenolics provides the basis for this investigation.
Key points and implications
For the experiments in this study, differentiated CaCo-2 enterocytes were treated for various time periods (typically 24 hours), with a mixture of cholesterol analogues (oxysterols, at a final concentration of 60 μM). To study the effects of olive phenolics, a phenolic-enriched extract was prepared from extra virgin olive oil (Bosana cultivar, Villasor, Cagliari, Italy – South Sardinia), and CaCo-2 cells were treated with various concentrations for 30 minutes prior to treatment with the oxysterol mixture. Following cell treatments, various commercially available kits were utilised to measure pro-inflammatory cytokine and chemokine levels, nitric oxide production, hydrogen peroxide production, and intracellular glutathione levels. Further, immunoblotting was performed to investigate cellular inflammatory (p38, MAPK-NF-κB), pathways. As anticipated, oxysterol treatment resulted in a strong MAPK-NF-κB pathway mediated inflammatory environment including increased production of cytokines, oxidative species, and nitric oxide, and reduced levels of glutathione. The findings indicated that pre-treatment with the phenolic extract attenuated these effects by dampening the inflammatory pathway and returning nitric oxide to control levels. Overall, these findings highlight the molecular mechanisms which may potentially account for the prevention of diet-induced gastrointestinal inflammatory conditions.
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