Adaptation in Caco-2 human intestinal cell differentiation and phenolic transport with chronic exposure to phenolic-rich blackberry (Rubus sp.) extract

Authors: REDAN, BENJAMIN - Purdue University; Albaugh, George; Charron, Craig; Novotny, Janet; FERRUZZI, MARIO - Purdue University

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/12/2017
Publication Date: 3/24/2017
Citation: Redan, B.W., Albaugh, G.P., Charron, C.S., Novotny, J.A., Ferruzzi, M.G. 2017. Adaptation in Caco-2 human intestinal cell differentiation and phenolic transport with chronic exposure to phenolic-rich blackberry (Rubus sp.) extract. Journal of Agricultural and Food Chemistry. 65:2694-2701.

Interpretive Summary: As evidence mounts for a health-protective role of dietary plant phenolic compounds, the importance of understanding factors influencing their absorption into the body increases. Recent evidence has suggested that chronic exposure may impact absorption and metabolism of plant phenolic compounds. To explore this phenomenon, we grew intestinal cells in special cell culture dishes that would allow them to transport plant phenolics in a way that would mimic a real gastrointestinal tract. We exposed the intestinal cells to blackberry extract during their growth. Blackberry extract was selected because of its high content of phenolic compounds, especially the purple anthocyanin pigments. We found that the intestinal cells behaved differently depending on the timing and concentration of the blackberry extract. To understand how the transport changes might be happening, we assessed gene expression in the cells. Gene expression is the first step in the cells’ building of machinery to perform metabolism. Through gene expression, we observed changes in specific transporters on intestinal cells that helped explain how the intestine may be adapting to chronic exposure to dietary phenolic compounds. This work will be useful to scientists.

Technical Abstract: As evidence mounts for a health-protective role of dietary phenolics, the importance of understanding factors influencing bioavailability increases. Recent evidence has suggested chronic exposure may impact phenolic absorption and metabolism. To explore alterations occurring from chronic dietary exposure to phenolics, Caco-2 cell monolayers were differentiated on Transwell inserts with either 0 microM (control), 1 microM, or 10 microM blackberry (Rubus sp.) total phenolics extracts rich in anthocyanins, flavonols, and phenolic acids. Following differentiation, apical to basolateral transport of phenolics from an acute treatment of 100 microM blackberry extract was assessed from 0-4 h. Additionally, differences in gene expression of transport and Phase II metabolizing systems were probed. After 4 h, 1 microM pretreated monolayers showed significant (P < 0.05) differences in cumulative transport including 33-42% less catechin/epicatechin, 19-23% less flavonols, and 32% less dicaffeoylquinic acid. Pretreatment with 10 microM but not 1 microM extract increased (P < 0.05) transepithelial electrical resistance of cell monolayers, suggesting 10 microM pretreatment may impact cellular tight junctions. Finally, significant (P < 0.05) alterations in mRNA expression of key Phase II metabolizing enzymes and transport proteins were observed suggesting that adaptation to phenolic-rich blackberry extract may impact intestinal barrier function and transport of these compounds.