AHR and psoriasis: The binding of urinary PAH metabolites to AhR can mediate the production of reactive oxygen species (ROS), regulate the expression of noncoding RNAs (e.g., microRNAs), induce cellular differentiation of Th2, Th17, and Th22, and promote the expression of a variety of cytokines or inflammatory factors, resulting in a Th17 immune response and an inflammatory infiltrate that contributes to psoriasis pathogenesis [30].