Green Tea Polyphenols Mitigate Gliadin‐Mediated Inflammation and Permeability in Vitro

Scope Green tea, a polyphenol‐rich beverage, has been reported to mitigate a number of inflammatory and hypersensitivity disorders in laboratory models, and has been shown to moderate pathways related to food allergies in vitro. The present study investigates the impact of decaffeinated green tea extract (GTE) on the digestion of gliadin protein in vitro and the effect of physical interactions with GTE on the ability of gliadin to stimulate celiac disease‐related symptoms in vitro. Methods and results Complexation of GTE and gliadin in vitro is confirmed by monitoring increases in turbidity upon titration of GTE into a gliadin solution. This phenomenon is also observed during in vitro digestion when gliadin is exposed to the digestive proteases pepsin and trypsin. SDS‐PAGE and enzymatic assays reveal that GTE inhibits digestive protease activity and gliadin digestion. In differentiated Caco‐2 cell monolayers as a model of the small intestinal epithelium, complexation of gliadin with GTE reduces gliadin‐stimulated monolayer permeability and the release of interleukin (IL)‐6 and IL‐8. Conclusion There are potential beneficial effects of GTE as an adjuvant therapy for celiac disease through direct interaction between gliadin proteins and green tea polyphenols. Green tea extract prevents gliadin digestion through direct interactions between gliadin protein and inhibition of digestive proteases. Complexes formed between green tea polyphenols and digested gliadin have reduced abilities to stimulate intestinal permeability and inflammation in vitro. These findings suggest that green tea polyphenols may have a protective effect against celiac disease.