Baicalein induces CD4(+)Foxp3(+) T cells and enhances intestinal barrier function in a mouse model of food allergy

The incidence of food allergy, which is triggered by allergen permeation of the gastrointestinal tract followed by a T-helper (Th) 2-mediated immune response, has been increasing annually worldwide. We examined the effects of baicalein (5,6,7-trihydroxyflavone), a flavonoid from Scutellaria baicalensis used in oriental herbal medicine, on regulatory T (Treg) cell induction and intestinal barrier function through the regulation of tight junctions in a mouse model of food allergy. An allergic response was induced by oral challenge with ovalbumin, and the incidence of allergic symptoms and T cell-related activity in the mesenteric lymph nodes were analyzed with and without the presence of baicalein. Our results demonstrated that the administration of baicalein ameliorated the symptoms of food allergy and attenuated serum IgE and effector T cells. However, Treg-related factors were up-regulated by baicalein. Furthermore, baicalein was shown to enhance intestinal barrier function through the regulation of tight junctions. We also found that baicalein treatment induced the differentiation of Treg cells via aryl hydrocarbon receptors (AhRs). Thus, the action of baicalein as an agonist of AhR can induce Treg differentiation and enhance barrier function, suggesting that baicalein might serve as an effective immune regulator derived from foods for the treatment of food allergy.