AHR and psoriasis: In addition to these treatments, there are also new therapeutic agents available for psoriasis, such as tapinarof, which is an aryl hydrocarbon receptor agonist, and roflumilast, which is a phosphodiesterase 4 inhibitor [8]. Conventional oral systemic therapies, such as methotrexate, acitretin, ciclosporin, dimethyl fumarate, apremilast, and tofacitinib, are the treatment options for those with moderate to severe psoriasis [9].