Differential effects of T. monococcum cultivars on transepithelial permeability of confluent Caco-2 cells

Background: Celiac disease (CD) is a chronic enteropathy caused by the ingestion of wheat gliadin and other cereal prolamines. Cereals of baking quality with reduced or absent toxicity are actively required as alternative therapy to a gluten-free diet for CD patients. T. monococcum (AA genome) wheat species are among the most promising suitable candidates. Under physiological conditions, intestinal epithelia are almost impermeable to macromolecules such as gliadin. Several studies reported that CD is a condition in which paracellular permeability is enhanced and the integrity of the tight junction system is compromised so favoring the interaction of gliadin peptides with sub-epithelial compartment. In this contest, zonulin, a recently described intestinal protein involved in tight junctions regulation, is responsible for the altered permeability in CD subjects. Objective: In the present study we investigate the effects on permeability of gliadins derived from two T. monococcum cultivars (ID331 and Monlis) using Caco-2 cells differentiated onto insert chambers. Experiments were performed in comparison with T. aestivum (italian cultivar) as the positive control. Methods: Alcohol soluble gliadins were processed using an in vitro digestion model mimicking in vivo gastric-pancreatic intestinal processes. The human Caco-2 cell line was used as a model of the gut epithelium to predict the physiological behavior. Cells were 21 days differentiated onto insert chambers. Paracellular permeability of Caco-2 cells was evaluated by measuring the Transepithelial Electrical Resistance (TEER) at appropriate time-points after treatment. The release of zonulin protein was also investigated by ELISA. Results: As previously demonstrated, Triticum aestivum gliadin induced a significant increase in Caco-2 cell permeability. On the contrary, TEER value was slightly reduced in the presence of Monlis, and remained unchanged with ID331 gliadin (Figure). Moreover, both T. monococcum cultivars did not affect Caco-2 cell viability. Preliminary data suggest that T. monococcum exert a reduced zonulin release with respect to T. aestivum.