AhR ligands: Therapy or risk factor in food allergy

Abstract

Food allergy is the result of an aberrant immune response towards harmless food antigens. Tolerance induction is an important process in the prevention of food allergy. Oral tolerance is the result of the interaction between DCs and T cells and the cytokine milieu. In food allergy no oral tolerance is established, but the immune response is skewed towards a Th2 response. Although cytokines play an important role in T cell differentiation, recent data suggest a role for the aryl hydrocarbon receptor (AhR) in T cell differentiation. AhR ligands can influence the differentiation and expansion of T cell subsets. Especially, regulatory T cells (Treg) and Th17 cells can be induced by AhR ligands. Induction of regulatory T cells that suppress Th2 cells would be a promising therapeutic option in food allergy. Additionally, suppression of antigen presentation and cytokine production by antigen presenting cells would be an interesting drug target. When AhR ligands indeed can regulate T cell differentiation, the AhR could be an interesting target for the treatment of several immune-mediated diseases. We review here current evidence for AhR ligands which influence immune responses. Based on the existing data of these specific AhR ligands, we discuss whether patients with food allergy would benefit from oral AhR ligands.