Protective role of 6-formylindolo[3,2-b]carbazole (FICZ), an endogenous ligand for arylhydrocarbon receptor, in chronic mite-induced dermatitis

The skin is a sensory organ that recognizes physiologic and pathologic chemical stimuli to ensure self-defense and homeostasis. Aryl hydrocarbon receptor (AHR) is a chemical receptor that can bind and be activated by structurally diverse external and internal chemicals including dioxins as well as various phytochemicals and photo-induced chemicals with a wide range of affinities [1–4]. Upon ligand binding, the ligand-AHR complex translocates from the cytoplasm to the nucleus, binds to its specific DNA recognition site, and then upregulates the transcription of various responsive genes such as CYP1A1, which is a member of a multigene family of xenobiotic-metabolizing enzymes [1,2].