Department of Experimental and Clinical Pharmacology, Medical University in Lublin, Poland
AhR activation in CoV-infected cells. CoV activate AhR by means of AhR-activating ligand independent of IDO1. Upon activation AhR translocates to the nucleus to bind to genomic DNA and to generate downstream effectors such as AhRR, CYPs, TiPARP, and cytokines. IDO1 is induced by inflammatory factors, such as TNFα and interleukins 6 (IL-6) and 1β (IL-1β). AhR also enhances its own activity through activation of IDO1-AhR-IDO1 positive feedback loop prolonging the effects of AhR activation by other pathways. Activation of IDO1 in immune cells leads to release of kynurenine, a tryptophan metabolite, which is an endogenous ligand activating AhR. Exogenous ligands binding to AhR are dioxins such as TCDD.