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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Produce Safety and Microbiology Research » Research » Publications at this Location » Publication #312693
Title: Effect of Apple, Baobab, Red-Chicory, and Pear Extracts on Cellular Energy Expenditure and Morphology of Caco-2 Cells using Transepithelial Electrical Resistance (TEER) and Scanning Electron Microscopy (SEM)

Author
item FINOTTI, ENRICO - National Research Institute For Food And Nutrition (INRAN)
item GEZZI, RICARDO - Max Planck Institute For Experimental Medicine
item NOBILI, FABIO - National Research Institute For Food And Nutrition (INRAN)
item GARAGUSO, IVANA - National Research Institute For Food And Nutrition (INRAN)
item Friedman, Mendel

Submitted to: The Royal Society of Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/13/2015
Publication Date: N/A
Citation: N/A

Interpretive Summary: We participated in a collaborative study with Italian scientists at the National Council for Agricultural Research, Research Center for Food and Nutrition, Rome that investigated the integrity of Caco-2 cells grown on a porous support based on the transepithelial electrical resistance (TEER). This non-invasive new technique uses a constant direct current (DC) applied by two electrodes, one connected with the lumen side and the other one with the basolateral side of the cells. By applying Ohm’s law it is possible to measure the related cells resistance (R). If the chemical equilibrium of the cells is perturbed by an external substance, then they tend to restore the equilibrium. For this purpose the cells expend energy by activating a metabolic pathway in response to the chemical injury. This is reflected in the resistance value, which is monitored by TEER. Mathematical analysis of the data reinforced by scanning electron microscopy (SEM) were used to determine the effect of commercial apple, baobab (an African fruit high in antioxidative phenolic compounds), red chicory, and pear extracts on the energy and histology of the cells. It would be of interest to find out whether the new method using Caco-2 cells can replace a more complex method based on monkey kidney Vero cells we used to measure the toxicological activities of native and inactivated toxins, including ricin produced by castor beans, Shiga toxin (Stx2) produced by E. coli bacteria, and Staphylococcus enterotoxin A (SEA) produced by Staphylococcus aureus bacteria.

Technical Abstract: The present study investigated the effects of four food extracts on the Caco-2 intestinal cell line using a new transepithelial electrical resistance method (TEER) concurrent with electron microscopy (SEM). Caco-2 cells are widely used in transepithelial studies because they can be cultured to create a selective permeable interface similar to that between the intestinal lumen and the basolateral tissue. These cells absorb, secrete, and function as a barrier that limits the passive transepithelial diffusion of hydrophilic solutes from the digestive tract into the circulation. The intercellular tight junctions provide a limiting barrier to the movement of the solutes through the paracellular route. The integrity of this tissue must be maintained when studying cellular physiology. TEER provides useful information on cellular function when a tissue in chemical equilibrium is perturbed by an external compound (such as nutrient, drug, pathogenic microorganism or toxins). In order to restore this equilibrium, the cells need to expend energy that can be calculated through a mathematical TEER value. The change in energy from the equilibrium value depends on the time elapsed and the nature and concentration of the test substance. The results show that extracts of four commercial foods (with the total phenolic content shown in mg/g gallic acid equivalents) - apples (3.39), African baobab (130), red chicory (13.31), and pears (1.15) induced concentration-dependent changes in both the energy and histology (morphology) of the cells as well as the formation of mucopolysaccharide. These changes, reported graphically and mathematically, were altered in the presence of the free radical (oxidant) 2,2’-azobis (2-amidinepropane) dihydrochloride (AAPH). At the highest concentration measured, the food extract with the highest phenolic content (baobab) completely damaged the cells. The new simple in vitro TEER assay offers a novel approach to investigate the influence of nutrients, antinutrients, and toxicants on the physiology and morphology of the Caco-2 cells that may predict their behavior in the digestive tract.