Jaronen, MerjaQuintana, Francisco2014-12-022014Jaronen, Merja, and Francisco J. Quintana. 2014. “Immunological Relevance of the Coevolution of IDO1 and AHR.” Frontiers in Immunology 5 (1): 521. doi:10.3389/fimmu.2014.00521. http://dx.doi.org/10.3389/fimmu.2014.00521.1664-3224http://nrs.harvard.edu/urn-3:HUL.InstRepos:13454826The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor initially identified because of its role in controlling the cellular response to environmental molecules. More recently, AHR has been shown to play a crucial role in controlling innate and adaptive immune responses through several mechanisms, one of which is the regulation of tryptophan metabolism. Indoleamine-2,3-dioxygenase (IDO) and tryptophan-2,3-dioxygenase (TDO) are considered rate-limiting enzymes in the tryptophan catabolism and play important roles in the regulation of the immunity. Moreover, AHR and IDO/TDO are closely interconnected: AHR regulates IDO and TDO expression, and kynurenine produced by IDO/TDO is an AHR agonist. In this review, we propose to examine the relationship between AHR and IDO/TDO and its relevance for the regulation of the immune response in health and disease.en-USMini Reviewaryl hydrocarbon receptor2,3-dioxygenasetryptophan-2,3-dioxygenaseJournal Article2014-12-0210.3389/fimmu.2014.00521