Mucosal Immunoregulatory Properties of to Reverse Experimental Food Allergy.

The intestinal mucosa is lined by epithelial cells, which are key cells to sustain gut homeostasis. Food allergy is an immune-mediated adverse reaction to food, likely due to defective regulatory circuits. is a non-pathogenic bacterium with immunomodulatory properties. We hypothesize that the anti-inflammatory effect of dead .  on activated epithelial cells modulates milk allergy through the restoration of tolerance in a mouse model. Epithelial cells (Caco-2 and enterocytes from mouse gut) and macrophages were stimulated with . and induction of luciferase under the NF-κB promoter, ROS and cytokines production were studied. Balb/c mice were mucosally sensitized with cow´s milk proteins plus cholera toxin and orally challenged with the allergen to evidence hypersensitivity symptoms. After that, mice were orally administered with heat-killed . as treatment and then challenged with the allergen. The therapeutic efficacy was (clinical score and cutaneous test) and (serum specific antibodies and cytokines-ELISA, and cell analysis-flow cytometry) evaluated. Heat-killed . modulated the induction of pro-inflammatory chemokines, with an increase in anti-inflammatory cytokines by intestinal epithelial cells and by macrophages with decreased OX40L expression. , oral administration of . increased the frequency of lamina propria CD4CD25FoxP3 T cells, and clinical signs were lower in . -treated mice compared with milk-sensitized animals. depletion of Tregs (anti-CD25) abrogated . immunomodulation. In conclusion, these bacteria suppressed the intestinal inflammatory immune response to reverse food allergy.